Character Analysis
Tommy is Annika's brother and Pippi's other best friend. He too seems to be about Pippi's age, and of the Settergrens, though we never find out who's older, we kind of get the impression that Tommy's the older brother—if for no other reasons than that he's mentioned first and the initial description of Annika makes her sound littler.
As a boy, we sort of expect Tommy to be a little more rough and tumbly, and he is. He's also more willing to buy into Pippi's adventurous ideas from the get go and with less reluctance than his sister. But the fact that there is still hesitation on his part and that he feels safer with Pippi—a girl—around to protect him, helps to emphasize the leadership role Pippi takes on despite her age, size, and gender.
This becomes especially apparent when Tommy recognizes Bengt the bully but doesn't take him on (2.52), and when Tommy is scared to go up to the attic but calms himself "with the thought that the ghosts probably wouldn't dare hurt Pippi" (11.48). Good thinking, Tommy.