Warrior Cats/WMG

Sandstorm will have more kits soon after The Last Hope.
And she will be one of the oldest queens the Clan has ever seen. Firestar was on his last life and they know a war is coming. So Firestar and Sandstorm embracing the possibility that one or both of them might not return, spent one last night together. And just for drama, one of the kits will be the spitting image of his father, down to his personality. Sandstorm will name him Firekit, after his daddy.

When she dies, Hollyleaf will be reincarnated as Hermione Granger.
Hermione and Hollyleaf both start out as rule-abiding goody-goodies, which eventually lands both of them in trouble, but Hermione, after being saved by a pair of apparent rule-breakers, quickly learns and accepts that rules are sometimes meant to be broken, while Hollyleaf has a heart murmur at the mere mention of it. Also, Hermione is best friends with Harry Potter, who wields a Holly wand, though this could be a coincidence. They both presumably feel insecure and out of place where they are because of their heritages (Hollyleaf is a half Wind Clan Thunder Clanner and Hermione is a muggle-born witch) and appear to crave respect. Also, black cats are often classically associated with witches as familiars, and Hermione's familiar also just happens to be a cat.

The main propose of the rebirth is to see if Hollyleaf's spirit can do better on a similar path a second time, and make better choices. It makes the final leap of faith in delving towards the end of their respective arches to when they face their supposedly disgraceful heritages, in which Hollyleaf fails by lashing out and betraying her so-called 'code'. Hermione however, succeeds with flying colors by boldly declaring that she is proud to be a 'mudblood'.

Ashfur was drowning when Hollyleaf found him.
Even though she wanted him to die, Hollyleaf cared a lot about the warrior code. So, she tried to save him. but, because she wanted him dead, but she also had to obey the warrior code, she got confused and ended up biting him in the throat instead of trying to pick him up. seeing that he was dead, she let him float down the river instead of bringing him back and being blamed.

Leafpool and Ashfur were actually somehow connected
If Ashfur was training in the Dark Forest *more likely forcibly, Hawkfrost and all*, he showed no signs of it. It would also explain part of the as well. Leafpool may have felt bad for him because she treated his wounds from the fights. Beats the 'he was a good warrior' excuse, anyway.

The Thunder Clan is the USA.
Acceptance of diversity and outcasts? Interfering in other clans businesses? Most varied land of all the clans? It all makes sense now! No idea who the other clans would be though.
 * I would find it very amusing if Shadow Clan was Russia.

One or more of the characters is a Time Lord.

 * Heavystep!
 * Rock! And the stick is his TARDIS!

Ravenpaw is Scourge's Son.
After browsing the allegiances in Into the Wild, you may notice that there were no black tomcats in Thunderclan besides Ravenpaw. Who's another black cat? Scourge.
 * So Firestar is Ravenpaw's uncle...?
 * Jossed, Ravenpaw's father is Fuzzypelt. It was confirmed on Vicky's Facebook.

Alternately, Scourge and Sandstorm mated.
Squirrelflight and Leafpool are, in fact, Scourge's daughters. This would explain Squirrelflight's one white paw- something that has only been shared by Scourge- as well as her personality. It also might account for Hollyleaf's. Since the three are still Firestar's kin, (distantly) the prophecy still works.
 * Actually, since Firestar and Scourge are half-brothers, the white paw was probably just a gene given by their father, Jake, though he wasn't mentioned to have had a white paw. Theory still works, though.
 * Doesn't really when you consider the timeline (or biology), though. A cat's pregnancy lasts two months/moons. We can estimate that Firestar and Sandstorm left about...eh, let's say a week after the epic battle. Traveling and rebuilding SkyClan, together, must have taken at least a moon or two, perhaps more. Sandstorm showed no signs of plumpness throughout Firestar's Quest, so Squirrelflight and Leafpool must have been conceived long after Scourge was dead. Word of God dismissed the theory herself, although this is WMG, so...
 * And the Hollyleaf thing doesn't really make sense. Hollyleaf rabidly supports the Warrior Code, whereas Scourge is pitted against it. Plus, Hollyleaf . Although, this could've been an intense plot point if it were true.

StarClan cats are powerful enough to alter the fabric of reality.

 * And this is what allows them to walk in cats' dreams, enter the living world, and such like that.

Jay's Wing is Skystar.

 * When Jayfeather went into the tunnels and came out in the place of Jay's Wing, Jay's Wing had to have gone somewhere, right? But clearly he didn't go to Jayfeather's era--someone would have noticed a copy of Jayfeather wandering around and smacking into trees, wailing "I'm blind!" Clearly, Jay's Wing was sent to a time where he was never reincarnated; he would have forced another reincarnation to some other era if he had (Sense? What's that?). And we've no idea what Skystar was like (though it would be safe to assume that he's a grayish color, judging by his name), right? Then perhaps Jay's Wing was dumped into the time of the early Clans, passing through the lake area...
 * Jayfeather isn't a reincarnation of Jay's Wing: they're the same cat in a Stable Time Loop created by Rock. This can only mean that: Rock is a Time Lord and the stick is his TARDIS!
 * How do we know Jay's Wing went anywhere except the ancient cats' equivalent of StarClan?

We haven't seen the last of Ashfur.

 * Though fans have asked where he went after dying, Vicky has been almost as vague as she has with . As "villains" go, he was fairly pathetic, lasting about three chapters. You've also got Leafpool's outpouring of emotion for him, which was so strong that Jayfeather thought she was in love, but gets handwaved in the next book as being "Oh, he was a loyal warrior and I'm sad he's dead." Plus, if really does come back as a villain in the next series, it would make sense for the only one she actually killed so far to make a reappearance from StarClan or TPoNS.
 * In addition to the above, when This Troper used the Warriors email address to ask him where he went, he told her that a twoleg named Vicky told him to to say.
 * But isn't the Warriors email address run by fans, and unofficial?

StarClan grew bored one day, and decided to give Heavystep nine lives.

 * Why else would he die so frequently, only to return the next book? Perhaps StarClan found it to be too tedious to toss out prophecies. So they convinced a med cat or two to lug him to the Moonstone/Moonpool and let them give him nine lives. They figured he'd never do anything rash, so there would be no harm. Whenever he died of one illness or another, he'd escape and return to RiverClan, who may or may not have been on the secret. StarClan had the benefit of screwing with everyone's minds, and for once in their afterlives they got to do something For the Evulz.
 * Frequently? He only came back once, after his greencough in Sunset. In fact, he only makes one non-Allegiances appearance after Sunset, and disappears from the Allegiances altogether after Power of Three. There are possibly two other cats (at least) that have come back once as well: Smokepaw/Smokefoot (fell off a cliff in Dawn), and Tornear (who was mentioned in The Darkest Hour as "lying motionless" while it mentions that the Clans have sustained losses in the BloodClan battle.)
 * He was an elder then, and had likely lost 7 of his lives by that time. After all, you don't get the name "Hevystep" by being agile and quick. And it was confirmed Smokepaw and Smokefoot are two different characters.
 * I thought Tornear was dead too, but he could have randomly been unconscious.

'Code of the Clans' and 'Rise of Scourge' were written by Unreliable Narrators.

 * 'Rise of Scourge' is Scourge's maddened attempt to justify his actions and make himself look harmless in his own eyes. His 'real' rise to power was much more sinister. First of all, "the dog saw his shadow and thought he was a monster?" If you believe that, I've got a bridge I'd like to sell you. Second, it's clear that Rise of Scourge skirts over the culture of fear portrayed by Barley (and who are you going to believe, the kindly old hermit with nothing at stake or the murderous dictator?) -- who's to say it didn't skirt over more?
 * 'Code of the Clans', on the other hand, is presented by Leafpool to an unnamed loner. For a start, there's a natural instinct to portray one's lifestyle in a positive way (for example, the way the questionable rule demanding absolute allegiance to the leader is portrayed as being a mistake made in the name of a crazy leader) showing. And look at the story explaining the dangers of cross-Clan relationships. On one level, this is just the basic story told to kits; it's been passed down for generations, and is probably skewed a little in order to convince kits not to emulate the behaviour shown. On another, it's also coloured by Leafpool's own experiences. We all know how her cross-Clan affair ended. Also, observe the way Darkstripe's eating prey before feeding the elders (a crime committed by Firestar in book one) is shown to be Darkstripe's first step on the path to darkness. How would Leafpool even know anything about that? At best, it's third hand, with Longtail telling it to Leafpool (and would he do that?), or made up out of whole cloth.

Pinestar is Firestar's father.

 * Pinestar had a reddish pelt and green eyes like Firestar. It has also been commented many times that Firestar has true heart of a warrior and is naturally gifted in hunting and fighting. This would then make Firestar, Scourge, and Tigerstar all half-brothers....
 * This has been disproved by Word of God, though.
 * Although the idea was suggested by a fan shortly before the release of Bluestar's Prophecy, to which Vicky replied she wished she had thought up the idea...
 * Wait, when he became a kittypet, maybe his name changed to Jake?
 * No, because Jake showed up in the same book.

Flametail is going to die.

 * It's been said that Night Whispers will be in his point of view. The blurb for the book says one cat will make a stand for what's right, but at a price. This may mean that Flametail will try to stop something bad from happening and get killed for his troubles.
 * Actually.

Sol is a robot.

 * Think about it: he never expresses any emotion other than fleeting rage, he's charming for no explainable reason (as is R. Daneel Olivaw of the Foundationverse, another famously realistic robot), and he knew that an eclipse would happen when NO ONE ELSE DID (this suggests that he was programmed with eclipse schedules for the British Isles). All of this can only point to one thing: Sol was built by R. Daneel and then sent through the Foundationverse-Warriors trans-continuity vortex to bring about the rise of Galaxia!

Sol is a member of the Dark Forest incarnate.

 * (Think Cinderpelt, but he remembers everything.) This could be the reason he knew the eclipse was going to happen and why he tried to stop ShadowClan from believing in StarClan, so he could recruit warriors for the Dark Forest. Also why he knows so much about StarClan; he probably used to live next door to them.
 * If you don't believe in Star Clan, you don't go to the Dark Forest.

Sol has XXY genetics and Redtail is a functional hermaphorditic chimeria
They are both male calicos (Well Sol is a tortie). Male Torties are rare, and virile ones are rarer. - The only way that Redtail could have the colouring he does and have sired offspring is that. It's quite possible, it means that when before he was born he had a sister who was developing next to him. However their fetuses merged at a very early stage. It ended up with mostly her body and the reproductive parts of both a male and female cat. However he identifies fully as male.

Swiftbreeze and Robinwing are littermates.

 * Robinwing, a brown she-cat with a ginger splash on her chest had Frostfur (white she-cat) and Brindleface (grey tabby). Swiftbreeze is tabby-and-white. It's safe to assume that she's a grey tabby, since some of her kits are variations of grey or black. Frostfur and Brindleface seem to look more like Swiftbreeze than their actual mother. It could just be the father's genetics, of course, but these two being sisters seems to be a reasonable assumption.

Rainwhisker was Molepaw's mentor.

 * Upon drawing up a list of all possible mentors for Molepaw, this troper concluded that Rainwhisker was the only option. Brambleclaw, Dustpelt, Sandstorm, Brackenfur, Cloudtail, Thornclaw, Ashfur and Spiderleg all had apprentices at the time; Brook and Stormfur were still getting used to the forest, making them unsuitable mentors; Sorreltail and Brightheart were said to have never had apprentices; Leafpool has never mentioned an apprentice that came before Hollyleaf; Ferncloud and Daisy are more or less full-time queens; and Firestar seems to only take on special cases. The only cats to have ever brought up Molepaw are his parents and sisters, and no one has ever mourned him as a mentor would. Rainwhisker and Molepaw both died in between the second and third arcs. For this theory to work, Molepaw would have died before Rainwhisker, since he would need a replacement mentor if Rainwhisker died first.

Rock was using Jayfeather.

 * Yellowfang said that when dead cats were forgotten by everyone they fade away. Rock lured cats into the tunnels and showed Jayfeather the stick in the hopes that they would find and remember him and the other cats who had died in the tunnels so they wouldn't dissappear. On page 161 of Dark River the stick says "Thank you, Jaypaw. We will be remembered as long as you guard us."
 * Or maybe the stick was really a horcrux and Rock was really alive, and that's why he grew so wretched- living for hundreds of years with no food in a cave. And no, WMGs don't have to make sense.

Sharptooth escaped from a zoo.

 * Mountain lions are not native to Britain, but that doesn't necessarily mean that Warriors has to be on "an island in the middle of the Atlantic". Sharptooth could have escaped from a zoo in any of the three known Twolegplaces, and found its way to the mountains (the closest thing it would find to familiar territory).
 * This troper subscribes to this theory!
 * Doesn't explain the wolves, though.
 * They escaped too!
 * Or it was some kind of reintroduction program to return wolves to Europe, like with the beavers.

Hollyleaf will kill Leafpool in the next series, whether Hollyleaf is dead or not.

 * My thinking is that Tigerstar was able to injure Lionblaze even though Tigerstar is a ghost. So, why wouldn't Hollyleaf be able to kill Leafpool? She almost killed her once already.

Hollyleaf left the yarrow outside the camp in Night Whispers.

 * When she was an medicine cat apprentice, in The Sight, Hollypaw didn't know tansy from yarrow. She then became a warrior apprentice, so she wouldn't have gotten any more training in herbs. Tansy would have been useful to Jayfeather. Hollyleaf tried to help (from wherever she is, living or dead) but got the wrong herb.
 * She might have left the squirrel, too. And it might not have been help: it could have been signalling Squirrelflight and Leafpool, the two cats we can be fairly sure Hollyleaf will most want to destroy.
 * Proven and a tad dis-proven in The Forgotten Warrior when somebody asks "Wait was it you who left the Yarrow?" Hollyleaf:"Yes I overheard that you needed it so I went to find some" (Not exact word for sadly I don't have the book at the moment but this was proven)

Lionblaze will kill Breezepelt

 * First, Firestar killed his half-brother Scourge. Then, Brambleclaw killed his half-brother Hawkfrost. Since Lionblaze and Breezepelt are also half-brothers, they might continue the pattern...
 * Don't forget about Graystripe and Darkstripe!

Minnowtail is Hawkfrost's kit, or at least she thinks she is.

 * We haven't seen much of Minnowtail, it's true, but from what we do see of her she doesn't really seem like the kind of viciously ambitious/vengeful cat who'd want to take over the Clans, like Breezepelt is or Hawkfrost was. It's possible she just thinks she's getting extra training, like Lionpaw thought, but now that there are all the other Dark Forest "apprentices", some of whom are outspokenly enthusiastic about the plot to take over, she would've realized sooner or later. But if Hawkfrost has told her he's her dad, then she might figure she has to be on his side.
 * Also, Minnowtail and her two siblings have much darker pelts than their pale-gray mom, Dawnflower, and two of them are tabbies, which Dawnflower is not. Hawkfrost is a dark brown tabby.
 * Even if Hawkfrost isn't actually Minnowtail's dad, Hawkfrost might tell her that he was, to recruit her. If Dawnflower never told who her mate was (and as this was back at the beginning of New Prophecy, when queens didn't have to tell, she may very well not have), then Minnowtail wouldn't know any different, and would probably believe him.

Thrushpelt and One-eye are Robinwing's kits.

 * Both are a shade of grey; Thrushpelt is sandy grey, while One-eye is pale grey. Robinwing's daughter, Brindleface, is grey, and her other daughter, Frostfur, has a grey kit, Cinderpelt. Thrushpelt is said to have only been a warrior for a quarter moon when introduced in Bluestar's Prophecy, and losing her sight in one eye would have caused Whitepaw's training to be postponed until she was fit enough to continue. The only other cat we know in this age range is Dappletail, who seems to have been One-eye's Heterosexual Life Partner.

Rock and Jayfeather are the same cat

 * Jayfeather taught the Ancients how to be like the Tribe, and stayed with them, becoming their first Stoneteller and changing his name to 'Rock', as a tribute to his spirit advisor. After his death, he became a sort of spirit guide to his past self, who lived in the future. In the process, he created a Stable Time Loop much like the one mentioned in the "Jay's Wing is Skystar" theory, where Jayfeather would travel back in time and start the whole process again. I know, I'm probably either eccentric or plain out of my mind, but WMG doesn't have to make sense...

There will be a movie!

 * HAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!
 * But Vicky will supervise it, thus pleasing the Unpleasable Fanbase, beyond what they would already be complaining about.

Spottedleaf is afraid of fading away, so she's trying to prevent it.

 * Yellowfang mentions in Fading Echoes that StarClan cats fade away when they are completely forgotten. Spottedleaf knows about this, and so she appears to as many cats as she can so that she isn't forgotten. After all, the living cats alone that have seen her in StarClan are Firestar, Sandstorm (FQ), Echosong (FQ), Leafstar (FQ/SD), Leafpool, Squirrelflight (Dawn), Daisy's kits (if you count them in Sunset), Willowshine (Sunset), Poppyfrost (The Sight), and Ravenpaw (Shattered Peace). With as many cats as possible remembering her and talking about her to their Clanmates, she's guaranteed to stick around for a while.

Cat's reincarnate when they fade.
My theory is that they are reincarnated as a similar cat, with no memories of their former life. However, since this takes a long time, nobody is aware of it.
 * When a cat dies, they go to SC/DF. When everyone living forgets about them, they fade away. But what happens then?

The "lion and tiger" prophecy in The Darkest Hour was really talking about what would happen if the Clans didn't join together to defeat BloodClan.

 * "Four will become two" obviously means that the Clans will divide. "Lion and Tiger will meet in battle" means that the divided Clans will meet and battle. "and Blood will rule the forest" means that BloodClan would take advantage of the battle and take over the forest.

It's All Just a Dream and only when Firestar loses his final life will it manifest

 * The reason for the series getting weirder and having more Wall Bangers and weird prophecies is Rusty is still at Twolegplace dreaming, he'll only wake up when Firestar "dies"

Mapleshade is still taking revenge on her mate's bloodline.

 * Two of the RiverClan Dark Forest trainees are Hollowpaw and Minnowtail. Hollowpaw is the apprentice of Reedwhisker, Mistystar's son. Minnowtail is the daughter of Dawnflower, who is likely one of Mistystar's kits, due to the fact that she became an apprentice in the same book that Mistyfoot went back to her warrior duties. Mapleshade will use them to take advantage of her mate's bloodline.

Sol is a shapeshifter.
This is why he was able to predict the eclipse- he found out about it as a human.

One of Stormfur and Brook's kits will grow up to take a ShadowClan or SkyClan mate.
Stormfur has ancestry from three of the Clans (RiverClan, obviously, ThunderClan, and, according to Crookedstar's Promise, WindClan (Crookedstar's mate had a WindClan father); his kits will also have Tribe blood. One of them ends up taking either a ShadowClan or SkyClan warrior for a mate (this troper's money is on ShadowClan, since SkyClan appearing by the end of OotS is doubtful). The next arc after the prequel series will center around either Stormfur and Brook's grandchild, who will end up becoming mates with a SkyClan cat, or the child of said pairing; the prophecy for that series will involve a 'child of all the Clans,' a.k.a. a kit with ThunderClan, ShadowClan, WindClan, RiverClan, SkyClan and Tribe ancestry.
 * Greystripe's mother was Spottedleaf's sister, so the kits already have SkyClan blood.

The three are result of StarClan's attempt to create Kwisatz Haderach.
To do this, they needed to combine fresh blood of a kittypet, ThunderClan and SkyClan, and the chosen had to be born from a medicine cat. Spottedleaf was cat originally chosen for this task, which is why she had shown interest in Fireheart, but after her death they needed somebody else. Since Cinderpelt didn't have the SkyClan blood, StarClan asked her to convince Fireheart to mate with Sandstorm, and to train one of their daughters as a medicine cat. Spottedleaf watched over Leafpool to make sure that she would fulfill StarClan's plan of kwisatz haderach, which succeeds, giving birth to the three.

Firestar is the ancestor of Puss in Boots.
They're both red-pelted and heroic. At least, I think Puss is heroic, i haven't read the story.

Bluestar was never mentally stable
Look at the depression she goes through when Moonflower dies. And again with Snowfur. She is easily wracked with grief, her belifs shaken. I'm no psychiatrist, so I don't know where that stands in between "Easily grief-stricken personality" and "Mentally reliant on those one is close to". Her beliefs and trusts are, and always were, fluid.

Sol and Rock are the Dark Forest and StarClan Founders Respectively
This explains why Sol always trolls everyone, and why Rock knows so much. They're founders! (This also makes Sol the Big Bad, which does make a lot of sense.)
 * Not necessarily...

Scourge's Soul Is...

 * Floating around, waiting for a newborn cat with a tragic future to take over.
 * In human hell, as Satan's right hand man.
 * Not likely, "Hell would have had the cat as its courier, could it have converted feline pride"
 * Already reincarnated.
 * Reincarnated as Sol.
 * Anything else?

Warrior cats takes place in the same universe as Cats
It is just that Cats takes place in London while Warriors takes place in the countryside.

Sol has nothing to do with the Dark Forest
Sol is trying to persuade everyone away from Star Clan. I'm pretty sure that he doesn't believe in Star Clan. Thing is, if you don't believe in Star Clan, you don't believe in the Dark Forest.

Firestar is descended from ThunderClan's first leader, Thunder.
On the Warrior Cats wiki, Thunder is described as strong, courageous and determined. Hmmm. He also has fur like autumn leaves. Reddish, perhaps? Obviously, before becoming a leader, Thunder mated with a pretty kittypet queen. A few generations later, and Jake was born. Why Jake? Well, one, that's where Firestar gets his fur color from and two, Jake, Firestar and Scourge were all drawn to the forest.

Lionblaze will end up being leader of Thunder Clan.
Since Word of God says that Brambleclaw won't end up being the leader, we can assume that he's going to die before Firestar does. Considering how long Firestar's been leader, and that after Omen of the Stars ends the next series will be about the beginning of the Clans, this troper will be highly surprised if Firestar doesn't end up dying, initiating a End Of An Era moment. Brambleclaw will die in the fifth book; considering that Lionblaze is part of a prophecy and seems like the best choice, Firestar will appoint him as deputy. In the last book, Firestar dies, Lionblaze has an Awesome Moment of Crowning, and this section of the Clans' history ends with the Clans continuing on with their lives.
 * Actually, I read the fifth book, and nobody dies. However, there's still room in the 6th. Probably during the great Dark Forest Battle, they'll both die, and Lionblaze will be a last minute type thing.
 * Jossed.

Mistystar's nine lives were give by...

 * OP's list
 * Bluestar
 * Oakheart
 * Graypool
 * Mosskit
 * Stonefur
 * Leopardstar
 * Crookedstar
 * Feathertail
 * Silverstream

If Lionblaze is made a leader his lives will be given by...

 * OP's list
 * Ashfur
 * Bulestar
 * Spottedleaf
 * Firestar
 * Skywatcher
 * Wind (his ancestor)
 * Brambleclaw (if dies)
 * Molepaw
 * Yellowfang

Squirrelflight Will Be ThunderClan's Next Leader
Because I find this scene hard to get out of my head. Brambleclaw preparing to make a charge on the Dark Forest that he knows is suicidal, with his last words being, "Tell Squirrelflight I love her, and that... she is the next leader!" And also, she does have good leadership qualities.
 * Jossed.

Firestar will be able to visit SkyClan's version of StarClan after he dies
He gave his second life in the service of SkyClan, which 'lives' with SkyClan's warrior ancestors. This anchors him there partially, so he will be able to look in on the living SkyClan cats whenever he wants, and walk in their dreams.

The Stick works similarly to SCP-140
In the original timeline, the cats who lived in the distant past of the forest were wiped out because they refused to move. The stick was a record of this happening, and whenever Jayfeather did anything to help Fallen Leaves, the record lengthened -- the first time in Dark River where five more cats were edited into the timeline, and a second time when the timeline was changed so the cats moved after all. The Tribe of Rushing Water is actually a completely different group of cats.