A brotender is a bartender who is also a close friend. A brotender looks after his friends like he looks after his bar. Making sure they don't drink too much or hit on married women with angry jealous husbands. If need be the brotender will give you a ride home.
Dude, Brian, I'm so glad I have you as my brotender. Without you that Marine would have kicked my ass if I had hit on his wife.