The Laugh and The Lol are canonically brothers. They both are featured on a trailer before Version 1.63.0 was released.
One day, as both brothers were at a campsite, The Lol showed The Laugh a brand new green knife. Because it was the same color as him, The Laugh wanted it for himself. This led to a fight between the two that ended up terribly as The Lol pushed The Laugh into the water. Watching as he sank, The Lol ran away in fear, leaving The Laugh to drown and become a Revenant.