Loveless/WMG

Seimei is actually Voldemort

Think about it: he's cruel, manipulative, has a creepy obsession with the main protagonist and the entire story is his fault. Kouga "borrowed" him from Rowling.
- Nisei could also be Snape. Actually, no.

Ritsuka is actually dreaming everything, while Seimei is making everything unfold as he sees fit.
- So Ritsuka's actually in a coma, which is why he doesn't remember anything from the past ten years.

Because.
Also to see all of the lovely Internet Backdraft among the more rabid Yaoi Fangirls.
Fighters are automatically attracted to their sacrifice, right? On the first day of school, she was the one who came to him and became close friends with him. Ritsuka also seems anti-social, but he stood up for her when she was being bullied. Also, when she was talking to their teacher, she said that she would be willing to die for him. Although it could seem that it's just a childhood crush, it still seems like something most 12-year-olds would be saying.
This theory gets my wholehearted approval if only because it made me spit soda laughing. What a way that would be to stick it to the fans!
The Tokyopop translation of the manga focused on one of the omake stories, where Yuiko (normally a champion at rock-paper-scissors) lost to Ristuka after he promised to do whatever she said. The translator noted that in doing so, Yuiko showed that she would be an excellent Fighter unit.

Most of the adults we see seem to still have their ears. So where are more kids coming from, if the adults are still virgins? Obviously they either go through grand-scale cellular mitosis or create new children in test tubes.
- Also, it allows for the more progressive pairings. It's possible for people of the same gender, even those who are related, to reproduce, because they just have to visit a lab for a new baby.
  - You know, of course, that this brings up the possibility of Ritsuka being Beloved's son.
Fake ears?
Who we see does not equal the standard demographic. Basically, we see a lot of virgins because that is who the series has as main characters, and the average normal adult is de-eared.
- Going by this, if you pay attention to the people in the background, most of them are de-eared.

In the beginning of the series, it shows Ritsuka as a lonely 12 year old with abusive parents
Loveless focuses on the power of the mind

The final episode itself shows Minami Ritsu working on something in the computer. On what was he working?
Ritsu has more than enough people in his "company" or whatever to create some very basic graphics and some simplistic MMORPG ripoff in case someone does not get properly hypnotized.
It would explain the final Mind Screw of an ending as a hypnotically-induced hallucination created by Seimei through the use of Minami Ritsu's engine. It would also prove Seimei to be as much of a Manipulative Bastard as he is in the manga.
When Soubi burns away inside the illusion after Ritsuka's reply, for a second you can see Seimei's face instead of Soubi's. That almost totally proves that the final Mind Screw is Seimei's work (even if the game engine is not by Minami Ritsu) and it hints that Soubi would have never done what he says inside the illusion.
I know it's different in the manga, I'm trying to somehow explain the Gecko Ending of the anime, which was psychologically awesome but a huge Mind Screw that came out of nowhere.