a very anti-social rabbit, mark spends his days developing equipment for Byster Bunny ( http://www.furaffinity.net/view/3196800 )

their relationship isn't very clear between them, Mark seems to only want to help the world with his devices, and Byster wants to be a hero, there are no signs of romance between them, dispite the fact that Byster flirts with him all the time

"huh? did'cha break the over-driver again, you should have it on all the time, Byster"