Punishment? What could I possibly have done to warrant punishment?

[His mind runs through his long life- he was never a bad person. Why would he be in a place specifically for punishing others?]

Do you think you deserve to be in Hell?

[If Eren doesn't think so, then maybe he's wrong about where they are. If he does... well, it doesn't mean much if Hythlodaeus still doesn't know exactly what he did wrong.]