[Eren's quiet for a moment. He'll resent the time Maruki spent without him forever, he thinks, though he's beginning to realize that it was necessary. Idly, he wonders if he and Maruki's souls might look alike. Sometimes he really does feel like they're the same person. The thought leaves him quickly enough. Eren has already seen Maruki's soul. Azathoth is a familiar friend to him now.

[All that being said, when Eren considers it...]

I think he does realize.

When he cares about someone, he'll stay right beside them, even when things can't be helped. But it did help, didn't it? He probably intended for it to.