When he "comes back" he can't even recall what could've made him so angry that he'd destroy someone's body like that...

If they managed to survive it, doubtfully so, Fritz does try to heal them. Bandage the wounds, try and close the crack in their skull, untwist their broken arms... He deep down knows it is kinda hopeless, but his savior complex says otherwise.

Not to mention that dark side of him burning with rage as it sees how he's forgiving and undoing all their hard work in punishing the poor bastard.