Bran, Puck, Robin
Bran is, in a word, passionate. Laughter comes easily, but so does anger. Everything is strong and immediate and perhaps not entirely thought through. He thinks with his heart (and a certain other part of his anatomy) rather a lot more than with his brain.
He is jealous, always afraid of losing what little he has and therefore hurts himself by wanting to hold it too tight, even if he never actually does.
He is angry at the world because he cannot understand why it doesn't want him.
Still, he loves words, loves talking and singing. Loves making poetry and sharing it with whoever wants to listen, even if that only happens to be a slug crawling across the stone he's currently sitting on.
Lust is never far off, and almost any emotion can be turned into it if you know how.
Proud, stubborn and wild, mischievous and impossible, and he wants so much for you to love him.
Puck
Knavish sprite, trickster, asshole. He tries to get into everyone's pants but doesn't really mean anything by it. He pokes and prods to find your sore spot, and when he's found it he pokes some more.
Everything slides off Puck, so no insult really sticks. He has no pride to speak of and shrugs everything off. It's all a game anyway. And sometimes, the game is rather cruel.
Puck is a mask and an act, but one he's been doing for so long that it is part of who he is these days.
Robin
Robin is the middle ground. Not quite Puck, but not quite Bran either. Robin is more depressed than angry, hating himself for all that he has done, all that he continues to do.
He is snarky and oftentimes a bit bitter, but there is still that fierce heart underneath it even if it doesn't burn quite as bright as it once did.
Robin will make deals out of kindness that a proper Puck should probably not make. He will seek the company of good people without having the intention of corrupting them.
Robin can still love. Can still care. He has an odd noble streak that will show itself every once in a while, completely at odds with his trickster persona.
All this is up to a point.
He stops himself, Robin does. Keeps it in check. Because if he does care about you, he doesn't want to hurt you. And if you get too close, you will end up hurt.
He can come off as self-pitying and melodramatic. He thinks he's allowed.