Seven ways words can hurt
I
Sirius's three.
He's out with his mother in order to buy a set of new dress robes befitting for his newborn brother's christening. He waits as she pays the snobbish lady at the shop, and sees, just outside the shop, a woman and her son. He watches as she bends down, gives the boy a hug, and tells him she loves him.
Sirius realizes his mother never did either of those things, and just as he does so, his mother smacks him around the head and tells him to pay attention and get out of the carrier's way.
II
Sirius's eleven.
He's sitting alone in one of the compartments, nervous, and he has never met a half-blood, let alone a Muggle-born.
A girl is the first to walk into the compartment.
That day he learns two things – "Mudblood" is not something nice to be calling people, and Evans has a very amazing left hook.
III
Sirius's sixteen.
He can't take it anymore. He has been swallowing what he really thinks ever since he decided to think for himself, and he can't do that anymore. And so he tells his parents, grandparents and basically all the extended family what he thinks of them, during a family reunion.
His father, not missing a beat, tells him and all the family that Sirius is a disgrace.
He leaves that day, hopping never again to return.
IV
Sirius's still sixteen.
He receives a letter from his mother, and what he thought would be apologies – not that he would accept them, he lather thinks, but it'd be nice to see them beg – turns out to be a formal notice of his exclusion of his parents will.
He is angry, and can't control himself, and happens to meet the worse person possible.
He slips.
The next day, Remus tells him to stay away.
V
Sirius's seventeen.
It's something that has been bothering him for some time, and when he finally acknowledges it, it takes him over two weeks to sort out what to do.
He finally does, though, and so he sets everything up nicely so he can look back fondly at that day in the future.
He goes and tells Remus how he really feels.
Remus says they can still be friends.
VI
Sirius's twenty-two.
War is everywhere.
Peter and James want to talk to him. He knows something is up and that it's bad, and he doesn't want to know it, but he hears anyway.
They say there's a spy, that someone has been feeding Voldemort information.
They say they have proofs.
They say that it's Remus.
VII
Sirius's thirty-four.
Remus says he's forgiven.