Sam;
Out of all of the Winchesters (by blood) that have ever been, Sam is probably the one who is the best with words. Dean has a habit of making jokes at the most inappropriate times, and John... Well, let's say he didn't always vocalise the right thing, in a different way. Even though the family tree doesn't stop there, it's evident this family aren't known for their poet-like speech. In consequence, Sam is practically a psychiatrist in comparison to those of his bloodline. He knows he can't solve all your problems with a single conversation; he isn't as naïve as that. However, he believes in talking it out, so whenever you're at the point of crying, he'll take your hand in his and try to sort through your troubles logically. Sam is a man of rational thinking, meaning it's his aim to directly solve your issues and do so as quickly as possible. He tries this kindly, though, and doesn't rush: his words to you are always sweet and he doesn't force you into saying or doing anything you're not comfortable with. Slowly, you begin to accept Sam's valid reasoning more quickly and more often, knowing that despite your scrambled but convincing thoughts, Sam will always know how to battle off monsters that aren't so literal as well as ones that are.
Dean;
When you're crying, Dean just holds you. He doesn't try and get anything out of you, or make an attempt to comfort you which he knows he can't succeed in. He simply sits on the floor or the bed or somewhere else he can cross his legs, and pulls you into his arms. He envelops you so you'll feel safe and secure, completely covered by him. He'll rock you back and forth gently sometimes. Every once in a while, he'll say "hey, I've got you". He places kisses in your hair quite often. He even sings to you sometimes. That's saying something, because Dean "doesn't sing". His favourites to sing to you are the chorus of Riptide by Vance Joy and Hate To See Your Heart Break by Paramore. The soothing of his voice puts you at ease, usually allowing your breathing to return to a steady rate. He'll breath in and out slowly and deeply, silently guiding you through. "I'm always here, okay sweetheart? For anything, anytime." He'll tell you, and kiss your head once more. He won't let go of you for at least an hour even when you've stopped crying. Only then does he tell you it's going to be okay. Being the 'suffer in silence' type of person, he recognises the importance in letting things out, even if he can't do so healthily himself. He knows crying is cathartic, so he let's you exhaust your upset before he gives you any words on the future and how things will turn out.
Castiel;
Feelings are still pretty new to Castiel, predictably. If you put the scale of how long he's been around into a day, he's probably only been attempting to do human things for a couple of seconds. Sam and Dean, having gone through trauma more times than you've had hot dinners, are not the greatest examples of what kind of feelings can bring your run-of-the-mill person down, and how to deal with them. Therefore, he knows he's helpless in a way when you become overrun with sadness or anger. Of course, he's felt these things before, but he can barely face them himself, let alone rely on his own knowledge and experience to cheer you up. So, he goes to your room and looks at your walls, plastered with photos like a teenage band obsessive, and picks out what you like. He makes sure he doesn't leave you for too long, though. He finds a TV show you like and in a flash, he's in a shop buying it, along with junk food: he knows you don't have a favourite, so he takes everything he can find. Not that you're complaining. As soon as he can, he gets back and sets everything up for you and carries you to the sofa. You watch and eat and he tries not to ask too many questions about the show... This is a crucial mistake, as you always find it funny when he does.