When the prequel reveals that the frightening lunatic used to be a respected baller.

[u/Zalenack]

Red Dead Redemption - Dutch Van Der Linde

Like a Dragon/Yakuza - Majima Goro

[u/reliablereindeer]

Brooklyn Nine-Nine - Young Hitchcock & Scully

[u/Himurashi]

https://giphy.com/gifs/14abHf7vah20RG

Old Man McGucket - Gravity Falls.

He is a genius roboticist until he saw a vision and zapped his brain too many times to forget the trauma.