The Kid Next Door - Is this Weird?

[KillarneyRose]

As I'm writing this, my daughters, ages 8 and 6 are out back playing with four of their friends who are all in the 6-8 year age range. The reason I'm posting, though, is because the brother of one of their friends, who recently turned 13, is out there playing as well.

This boy is nice enough; he seems a bit on the "slow" side and doesn't appear to have many friends his own age. Also, he is not involved in any outside activities (i.e. Boy Scouts, sports, etc.). So, often he tags along with his 7 year-old brother when he is playing with other younger kids.

For some reason that I can't quite put my finger on, this unnerves me. There's just something menacing about looking out the window and seeing this kid who's almost as tall as me playing with a bunch of first through third graders.

The younger kids don't seem to mind having him around, but is this sort of behavior "normal" for a 13 year-old? Should I be concerned?

Thanks!