When they're six, Sam's dad marries a woman named Kate Milligan who has a four year old son named Adam. Sam likes her, likes having someone he can call mom, someone who's around when John isnt. Dean hates her. Sam runs to Cas's house crying after Dean tells him he's a horrible person. "It's not my fault I don't remember my mom and everyone acts like it is." Cas's parents explain that Dean feels like John is trying to replace his real mother and is therefore upset. It takes a while before Dean finally apologizes.
When they're seven, they try to move Cas up a grade. He doesn't want to leave Sam and refuses, even though he's somewhat bored with his schoolwork.
When they're eight, Cas ends up in the hospital. Kids are mean and Cas is tiny. He gets pushed down the stairs and breaks his arm. Sam gets suspended for three days for beating up the kid that pushed him. Dean is immensely proud.
When they're nine, they have their first fight. They don't talk for three days. It's over something stupid, and a seven year old Adam plays owl between the two houses.
When they're ten, Sam tells his dad that he's going to marry Cas. Granted, he's on so much pain medication he thinks he's flying and doesn't remember this conversation the next day, but he says it.
When they're twelve, Kate dies and Sam doesn't know what to do. He stays at Cas's house more and more. John starts drinking and tries to move the family away. None of the boys want to leave, and Dean tells John that if he thinks about it he'll steal the Impala and take Sam and Adam back to Bobby's. John finally figures out how to deal and they stay.
When they're fourteen, Cas figures out that he's in love with Sam. He also figures out that he's not going to tell him. Ever. Sam's obviously known this since he was ten, but he figures it out a little bit more.
When they're fifteen, Cas gets his heart broken. Sam dates a girl named Ruby who teaches him how to kiss and who cheats on him with Cas's oldest brother Lucifer (who's 19 and right out of prison a third time). Then he dates a girl named Meg who tells him that she's pretty sure Cas is in love with Dean and breaks his heart. He's not sure what broke it; her or what she told him. Cas dates a girl for three days before freaking out and breaking up with her. He's not sure what possessed him to do it in the first place.
When they're sixteen, Dean smacks Sam in the head and tells him to stop mooning and ask Cas out already. "You've been in love with him since you were like, six." Sam's a little bit upset that even Dean could see it since he didn't think it was /that/ obvious. It takes him somewhere around three months and another lecture from Dean before he finally stammers out something resembling "I'm in love with you" when talking to Cas and turning to run. Cas grabs his hand and tells him the same. When Sam gets home, Dean gives him a high five.
When they're eighteen and going off to college, Sam gets incredibly nervous. He's going to Stanford, and Cas is going to another school in California, but they're almost an entire state apart. They still talk to each other every night and see each other every time there's a break. Twice in the first semester does Sam hop on a plane to go see Cas in the middle of the week.
Right after finals their last year, Cas breaks up with Sam. They stay broken up for almost six months. Sam's about to go into law school, and Cas is just too far away. Sam goes back to school, but soon decides it's not worth it. He goes back home (where Dean looks like he's about to kick his ass and Cas's) and tells Dean he just couldn't do it. That becoming a lawyer was too hard. Dean, with his genius ideas as usual, drags Cas to his house and locks him and Sam in a closet. Somehow it ends in Sam and Cas looking for apartments near Stanford and Dean regretting his part in the whole thing when they start making out.
A few years later, Cas talks to John about marrying Cas. "He told me when he was ten he was marrying you. Don't think I can stop it now."
Cas asks Sam about it, and Sam has no idea what John was talking about.
A few years after that, once they finally figure out what they're doing and decide to get married (for real), Dean's finally dating a girl seriously and Adam's been staring at Cas's second oldest brother Michael. Everyone's got their own happy ending.
(Note by Destiny: Except for Gabriel because I forgot about him oops bye)