Argggggh! Why didn't I study Japanese while in undergrad!?
It appears that evil-Sunao is going full-tilt on his plan for revenge. Apparently, Sora and Sunao were kidnapped and experimented on as children. There was a rescue attempt by Nanami and Shinichirou that was only partially successful -- Sora was rescued, but Sunao was left behind.
Now I'm just guessing, but evil-Sunao appears to be angry and resentful (understandably so) about being abandoned and is out for revenge. What isn't clear (at least to me from watching the raw of episode 11) is whether he wants revenge on Shinichirou (for abandoning him) or on Sora (for escaping the hellish experiments).
You see, as evil-Sunao and Shinichirou have their confrontation, zoned-out Sora staggers in clutching a knife. Evil-Sunao says something that unblocks Sora's memories, which leads to a massive mental meltdown. I'm not sure whether evil-Sunao wants Sora to stab himself or to stab Shinichirou. However, the point becomes moot because Shinichirou basically steps forward and impales himself on the knife -- to keep Sora from having to act and/or for atonement? -- while murmuring something reassuring to poor Sora. Evil-Sunao looks shocked, then runs off. Later, Sora wakes up a bit more clear-headed and has a long talk with Yoru.
Oh yeah. Apparently the experiments in question had something to with creating split personalities in people using fear as a trigger/suppression mechanism, for the purpose of making the perfect spies, secret agents, assassins, and whatnot. That goes a long way to explaining both Sora's and Sunao's whacked out behavior.
Well, all this definitely throws a massive speedbump into the Sora/Sunao and Yoru/Ran relationships. DAMN! Now I'm climbing the walls wondering how this is going to work out for everyone. Happily, I hope, but you never know. :P
::keeping fingers crossed as she waits impatiently for episode 11 to get subbed::