I think it's more to do with confidence and assertiveness than aggression sweetie. Aggression is as often as not about proving something, about forcing others to your way of thinking, sometimes through violence or coercion. By contrast, assertiveness is simply not being afraid to speak up when there is a need to do so, about standing up for your right to choose, or in this case, that of your friend.
Of course, Tekla is right. You do need to be careful still, read situations and pick your battles. There's a right and a wrong way of doing assertive - my brother is a good example of the right way ... when he speaks it's, in this quiet, assured authoritative voice people just listen to. He never gets angry or aggressive or stuff, but people listen. And importantly, he doesn't overreach - he is very careful in speaking on matters he doesn't know about or that don't affect him or people close to him directly. He'll give opinions about those if asked, but he won't go in with that certainty that he'll be listened to, and I think people learn to respect that he knows his boundaries. By contrast, many people try to pull assertive off all the time, but when they don't get their way they get belligerent and aggressive and obstructive.
So yeah, pick your battles, and when you can't pull assertive off, or it just won't work, remember that other great social lubricant, passive-aggressiveness, can also be really useful sometimes.
Mina.
