I can't help but feel as though Seiryuu is one of the smartest opponents Saitama has ever faced.
Why do I think this? Well, when he got beaten by Saitama he didn't get obsessed over it. He didn't get angry or declare him his rival or try to beat him to death despite the vast difference. He just got over it and moved on.
No other opponent besides Genos has just moved on after being beaten by Saitama, and even then Genos had to take an almost death punch to the face. Even though I think he's a giant prick, Seiryuu does have my respect for that.
And he's hot.
Fire emblem?
That's pretty much my theory for why he seems to think all this is okay. The little shit has been reading to many yaois, got convinced that it was the real deal, and tried to apply it to real life.
The thing about constantly raping Haruki and thinking that he'll still love him in the end? The Rape Is Love trope in yaoi manga. Saying I love you and expecting him to automatically love him back despite all the shit he did to him? Classic yaoi. Giving a half hearted apology, promising not to do it again, and expecting Haruki to fall into his arms or forgive him instantly? Happens all the time in yaoi manga. Blackmail and sex videos in order to get more sex? Where else but yaoi manga?
Seriously, it all makes sense now that I think about it in that light. Hikaru isn't a sociopath, he's just an idiot teenager who confused fiction with reality, believed in all the yaois he read in his off-time, and tried to apply it to real life only for him to slowly realize that no, the real world doesn't work that way.
Can I just say that -- besides the awesome sex scenes -- I love the fact that the uke has his shit together.
Like he's a hard worker, he studies, he's planning for his future -- totally not dependent on anyone else at all. In too many yaoi mangas the uke is just a pretty freeloader, or helpless and need of help, or just useless in general. This guy though, he can stand on his own. Which makes him all the more attractive in my eyes.