Oscar scrambled for a grip on the hood, his pale knuckles turning white he held on so hard. “B-but s-school is full of humans!” he stuttered out, his voice barely more than a frightened squeak. He couldn’t fathom how Sam tolerated being around that many bigger folk all gathered in one space.

I don’t think Oscar agrees with Sam about this being a good idea…

Read more here.

The difference between Brothers Together and Brothers Apart will be that Sam will actually be growing up with Dean. So instead of going from one extreme to the other like in the original story, it’s going to happen gradually. Sam will adjust as they both grow and it’ll feel normal to him to see Dean at his adult size by the time they get there. In this AU they’re going to be more adjusted to each other than they are in BA from the start.