He's lived for too long, and has too much to remember. Not having land means he has to try to remember everything like a human would, and trying to pack all of that information in his head affects him. One he has Alzheimer's. He has spells where he forgets everything around him for a moment or so before snapping back into reality. Also, he has PTSD from all the wars, mostly ww2 and the Russian occupation in east Berlin after. That's why he is hyper-emotional, hyper-sexual, a hoarder, goes on crazy impulses, can be delusional, and ends up distancing himself from others.
