we know that canonically asriel and kris were besties but at the same time. i just KNOW they were not immune to The Cain Instinct.
like take one look at kris and tell me they WOULDNT see asriel standing in the kitchen all ready for church with his dorky little shirt tucked into his trousers and decide to drop an ice cube down his collar. you cant.
asriel would bonk kris on the head with an empty cardboard tube