It just sounds interesting. I've read it in A Demon Lord's Hero. It's a F/SN x HS DxD crossover fanfic. They have to choose a sin they can control or they will receive a natural sin they cannot control. Like getting gluttony and they just eat until their stomach bursts and die. Or having pride thus they went to the path of the blade because they saw their own reflection on it. Does this exist anywhere else?