Update: I was unfortunately not aware of Shamus Young's severe criticism of Fallout 3 available here to link in the original piece and I regret that. It dovetails rather nicely with what I've written and it's much better executed than my piece. I strongly recommend anyone...
Keep in mind that the boy and his father will beckon the other if he needs some help.
If you stick near fires you'll stay warm.
Make sure you leave the other character in a safe place when you wander off.