I was going to quote that part too.
Confidence is all.
It has to be internal, though -- kids who are worried about this stuff and are told to "act confident" when they actually aren't redouble their mark of Abel.
Anecdote that really needs more time but will try to condense:
We have a neighbor who has issues of one kind or another. She's two years older than sozlet, and they played together sometimes when we first moved here, before sozlet knew many other kids, but it always seemed to end badly. Feelings were hurt, vaguely upsetting things happened (lying, bullying). And pretty much as soon as sozlet met other kids, the playing with neighbor girl stopped.
At their elementary school, kids two years apart are grouped together for recess and lunch time. When sozlet started kindergarten, one of neighbor girl's friends (then in 2nd grade) approached sozlet and first confirmed her identity and then said, "I've heard WEIRD things about you." Sozlet relayed this to me as a funny story. I was (privately) furious... what had neighbor girl been saying about sozlet?? But sozlet's reaction was just to laugh and move on.
I think that's one of those signal moments.
Sozlet has since gotten to know pretty much every kid within a 20-mile radius and is friends with most of them. (Coming up with her birthday guest list was a major chore, as inviting 57 kids was not practical.) She knows not only kids her own age but younger and older; siblings, hanging out at the pool, whatever.
Neighbor girl invited sozlet over to play the other day -- that's unusual, and I was a little suspicious. I asked sozlet later how it had gone... fine. Did neighbor girl ask a lot of questions? Yes. About what? Who she knows.
Neighbor girl seems very status-conscious. The invitation to play came after sozlet had a good friend over who is from a "popular" family (this girl and the girl's older sister, too, who is in neighbor girl's grade.) The fact that sozlet is friends with so many "popular" people seems to have elevated her status a great deal. Neighbor girl strikes me as someone who either bullies or is bullied -- she seems to think about this stuff a lot, what other people think about her, where she is on the totem pole.
Sozlet, meanwhile, is oblivious. She's friends with nice people and not friends with not-nice people, no matter who they may be.