Sort of both I think. The black haired guy definitely has some kind of memory loss and I think that the blonde guy dreams about how they used to be before he lost his memory.
I think he has memory loss, According to the raws Ryouta was being bullied when they were children and one time it ended up really wrong ( i mean it involed a KNIFE) Akito protects him and got a cut under his eye and when they run off i think ryouta jumped somewhere high and didnt land very well which caused him being confined for several years while Akito is just waiting for him to wake up. And when he woke up Hes finally had the crazy eyes
i think something shocking happened at that place,and he lost his memories due to the shock? i mean there was blood at the first panel,and that was a memory(i think?)
i'm not really sure, but you kinda can guess from the latest chapter, and i think because no one blame blonde guy for what happen to ryouta and he wanted to be blamed because he himself think that ryouta's accident is because of himself, he kind of got this fantasies/hallucination/dream about ryouta 'punishing' him for what happen.
ok so like does the black haired guy have a split personality??? or does the blonde hair buy just have fantasies ?? im confused