Demyx (Kingdom Hearts) is open for fourth-walling! He already pretty much knows what happened to the Organization and it's world anyways!

Mao (Code Geass)) will have to be a no-go for now, sob

Kael'thas (Warcraft III/World of Warcraft) Recognizing is a go but he has no idea of what he does re; the betrayal of his people (canon point is the Dalaran prisons in the WC3 Belf campaign just before Vashj busts him out). Keeping things hush hush about his future would be awesome! The poor thing just isn't ready for that yet