He had access to them, what did Akira think would happen?

Perhaps more insultingly than trying to kill him, Akechi looks briefly away in disgust. One 'Ren' was already enough, but...

"Then you're not the Joker I know. I've spoke to others from different worlds and different times. In this place it seems probable."

There's a strange sadness to it, almost. Like his realization that while both are together...they are, ironically, alone.