Katekyo Hitman Reborn/YMMV

And the Fandom Rejoiced: Hey everybody, the future arc's finally over!
- Yamamoto's return.
Arc Fatigue: The recently concluded Future Arc which makes up over half of the manga at this point. Was even longer in the anime due to two additional Filler Arcs in the middle.
Badass Decay: The only way to explain what happened to Adelheid Suzuki: she went from fighting evenly with Hibari to not being able to land a single blow on him within slightly more than a week. This is especially egregious when you consider that not only did she get a massive power boost from the "Vongola Sin", it was expressly stated that this power would continue to grow over the course of the next seven days.
Base Breaker: A few:
- Hibari: Half the fandom loves him because of his Memetic Badass anti-hero status the other half hates him, seeing him as a Creator's Pet Jerk Sue. It doesn't help that we see the other characters have to endure Training from Hell and every fight he participates in is an Anti-Climax
- Tsuna: Many see his reluctance to fight as a nice change from the cliche action hero. However, many fans are annoyed that he is still a whiny idiot and keeps losing at the beginning of each arc.
Belligerent Sexual Tension: ANY GokuHaru fanfiction writer exploits this, having at least 3 "Stupid Woman" in there. As for Canon...well YMMV on that, whether you think the relationship is Romantic or Not. It's much more likely it isn't romantic at all.
Complete Monster: Byakuran. ...Well at least the one in the Future Arc anyway. Oh the joy of alternate timelines. Daemon Spade is a borderline case as well.
Crowning Moment of Awesome: Well this is a shounen series, so almost everyone has plenty, Hibari in particular basically out-crowns himself every time he shows up.
Crowning Moment of Funny: The series was a gag manga before Mukuro showed up and the series grew its beard and still retains some pretty good humor in between all the fighting.
Crowning Moment of Heartwarming: And cue the "Awwws" in 3... 2... 1... Click!
Designated Protagonist Syndrome: Poor Tsuna
Draco in Leather Pants: Um... close to every single major villain to date?! As one fan made note, to be a villain in this series you must be FAB.
Ear Worm: A good number of the songs from the anime, openings endings or character songs can be guilty of becoming this.
Ensemble Darkhorse: Kyoya Hibari is statistically proven. He has always been number one in every poll to date.
- A recent poll has Squalo put in 4th place.
Evil Is Sexy: Boy is it ever in this series.
Fashion Victim Villain: Daemon Spade. Which is sad because for the most part he applied to the Evil Is Sexy trope... and then he went and possessed Mukuro. Now we have THIS. Standard fandom response is laughing your ass off.
Fridge Logic: Tsuna developed his X Burner technique in the future when he realized he could use his flames for offensive attacks by blasting said flames. Didn't he realised he could do this LONG AGO when he blasted said flame to protect Chrome and the Kokuyo gang when the Varia's mosca was going berserk?. Sure, it wouldn't have the sheer firepower of the X burner back, and it was purely a defensive move then but it would have still been a powerful move given that it stopped the mosca's laser cannon and the bullets from a Gatling gun.
Harsher in Hindsight: Reborn's early interactions with Lambo. Sure, we know how annoying Lambo is, about all that "rivalry" thing and that he's not gonna be killed even by grenades, but once we realize it's an adult hitman beating the living crap out of 5-year old kid... Dude, Not Funny.
Growing the Beard
I Knew It!: Pretty much what the entire fanbase was thinking when the Shimon family was revealed to be Big Bad of the Inheritance Ceremony Arc.
- Quite a few people predicted that Shimon had Earth-based flames, too.
- Some of the people who also saw the anime predicted Daemon Spade's role in the series in that same arc.
Launcher of a Thousand Ships: Tsuna, oh god, Tsuna.
- Chrome to a degree as well by virtue of being the only female amongst the guardians.
It Gets Better: Around volume eight. Chapter 62 to be exact.
Magnificent Bastard:
- Byakuran definitely fits the bill. In every single one of the multiverses.
- With the reveal of who really masterminded the time travel plot, TYL!Tsuna gets props for putting the kids in significant danger just to motivate his younger self. His own younger self can't believe it was really him.
- Daemon Spade managed to successfully pull a Grand Theft Me on Mukuro. Lemme just repeat that: He pulled a Grand Theft Me on MUKURO.
Memetic Molester: Hoo boy, this series has a decent number of them. To wit:
- Mukuro Rokudo's gonna have some goddamn fun with you.
  - Mukuro wants your body.
- Bird's... just Bird's. Gotta love the creepy old sadists...
- Depraved Homosexual Lussuria of the Varia. Who during his fight with Ryohei expresses blatant interest in him while simultaneously reveling himself to be a necrophiliac.
- Dino's a more arguable case, due to his grin when you see this first encounter with Hibari as his pupil.
- Glo Xinia. It is heavily implied during his encounter with Chrome that if Mukuro hadn't stepped in when he did, Glo probably would have tried to rape her.
- Spanner's wildly regarded as a pedophile due to his interactions with Tsuna, which included stripping him for no real reason and handcuffing him to his bed. His blushing face (in regards to the X Burner technically) and sudden Heel Face Turn don't help.
- Byakuran smiles constantly, loves *symbolic flowers*, kills off one of KHR's other memetic rapists, and has signature moves where he 'penetrates you'. Oh and let's not forget his image song where he asks you to 'give him your body'. Then there's his blatant obsession with Uni once she escapes his grasp. Although there is a good reason for it, the vibes are still there. Not to mention his grabbing of Tsuna from behind and whispering into his ear...
- Julie Katou wants you to know that you have "date plans" with him. And he will help you dress for them~ Shame this is all due to Daemon Spade possessing him
- Daemon Spade's a pedophile that wants your body. Nufufu~ How ironic that one of the Memetic Molesters above is a VICTIM for this guy.
Moe: Tsuna. Oh so much. Chrome too.
Moral Event Horizon:Mukuro's utter and rather brutal Lack of Empathy when fighting with illusions of the Kokuyo Gang raised a few eyebrows among fans considering they're the main source of his Pet the Dog moments.
Narm:
- Despite the clear amount of drama and "Oh Crap" moments going on in the most recent chapters of the Inheritance Ceremony Arc, the Fandom still laughed its collective ass off at how Daemon looks in Mukuro's body.
- Giant Byakuran head in the sky.
- The Bloody Twins, who were horrifying in the manga, look more like two stoned freaks in the original mugshot in the anime.
Nightmare Fuel: Here.
Periphery Demographic: Did the number of bishies in the story really convince you that this series was just for guys?
Tear Jerker: Go cry over the page here.
The Scrappy: Longchamp Naito. Near-universally despised by a large percentage of overseas fans due largely to his goofy appearance and rambunctious personality. there is a reason he only appeared in the manga...
Submissive Badass: Tsuna seems to fit the description to a freaking T.
Villain Sue: Daemon Spade seems to have studied under Nakago and Dartz in how to pull this off. Even the part where he ends up WAY too Easily Forgiven by his enemies right as he's dying, even though he'd been nothing but a Complete Monster 'til then.
The Woobie: Gokudera, especially when you learn about his past.
- Chrome also due to the hell she goes through. Her parents abandoned her to die, half her organs are missing, she's constantly belittled, and most recently she's been hypnotized and tortured by Daemon Spade purely to push Mukuro's Berserk Button.
- 20YL!Lambo, particularly when you realize, thanks to Byakuran, exactly what kind of future he has to return to.
- Uni, and by extension Luche herself. Luche was Blessed with Suck, received the less-than-beneficial end of the Cursed with Awesome stick shared by her other partners, and worse yet has to pass that on to all her future descendents.