[Congratulations, Sora, you're officially only the second person to ask that question without a 'the hell' in it. Also, you get a quizzical look for your fearless invasion of his personal space. Why do Riku's derps keep wanting to visit him?]

It's complicated. The short version is that I was attacked.

[The only reason you are not being made to get off his bed is because Riku wants him to be nice to you and Sephiroth's social skills do not allow for regaining his personal space without being an asshole.]