You'd be surprised what brothers are up for. I had a group of my friends that I played DnD with in highschool until we graduated and one joined the marines. We had a campaign to finish and a free spot, so I grabbed my little brother (he was about 13 then). He got so into it that he was having me help him pick prestige classes for his barbarian last time we played. Even the other guys got into the act, and now any character he plays is called Ug, Thog, or something the like.
"Nothing is ever easy."
"...You can't take the sky from me."