dude, DON'T GET A ROAD BIKE. he's 12, so if he has one of those, he'll probably get laughed at. same with hybrids. he's almost a teenager, so he probably needs a bmx or dual suspension mountain bike. MTB isn't my forte, but I love BMX. I ride a Mirraco. they're fairly cheap, and blow WeThePeople and Subrosa out of the water. if he's not gonna be riding much, or is new to riding, get him a Recruit.
http://mirrabikeco.com/recruit.html if he's any good at riding, get him a Fivestar.
http://mirrabikeco.com/fivestar_option.html I wouldn't go for a BLend unless you got money to spare. they ride awesome, but are high maintenance.