Heisen's MOOOO AND KRILLLL

Description

I wish this was a joke, I really do but I have to vent somewhere. I play Deadlock with two other people (sometimes three) but one of them consistently and always picks Mo & Krill. He never plays any other hero - no, he refuses to play another hero. We are always joking about it but it's seriously starting to piss me off. The stupidest thing is that whenever he manages to get a kill (he averages 4/6/7 like every match) he screams at the top of his lungs "MOOOOOOOOOOO AAAAAAAND KRIIIIILL". Me and the other friends I play with genuinely do not know what to do anymore. He always farms lane but somehow manages to only have 12k souls at the end of a 35 minute game. After the laning phase he just disappears into jungle and we do not see him (I do not count the times he spins up from the ground not anywhere close to any enemies). I am seriously starting to consider playing another game or trying to convince him to play any other character but he won't listen. He has 20 hours playtime and he has never played any other hero. What can I do?