Man of Honor?

Okay so I have two best friends that I do not really want to have to pick over being my maid of honor, and I do have a step brother who I am kind of close to (we are 12 years apart). I was thinking of maybe asking him to be my man of honor instead of having to deal with my friends fighting over the position. My fiancé doesn't really know him well but he has been in my life for 14 years and I would really love to include him in my wedding. Anyone else have a man of honor and if so, how did it go? What duties did he perform for the wedding?