Sam was stillness.
From the time he was little, John had marveled at it. He was such an easy baby, hardly any fuss at all. And when he got a little older, all John had to do was plop him down in his baby seat in front of the TV. The toddler would watch as though day-time television was actually interesting. And the cartoons – well, if John used the word zombie lightly, he would have used it to describe Sam.
By the time he learned to read (which happened to be the same time Dean learned), Sam could sit still for hours, never looking up. Probably could have gone longer than that if his family had let him. He'd lay on the couch or bed not moving more than was necessary to turn a page or occasionally flail a hand out in the direction of his soda or bag of chips – he wouldn't actually look up for it, mind you, just wave an arm blindly in its direction until he hit what he was looking for. They ended up with more soda stains on the couch that way …
Dean and John could be arguing about a hunt three feet away and Sam wouldn't notice. Not just wouldn't pay attention, he actually didn't notice. When he was finally called into a conversation – which usually required actually shaking his shoulder because calling his name didn't do any good – he'd blink a few times before emerging from whatever imaginary world he was in and saying "Huh?" There was never any indication that he'd known Dean and John were in the room at all.
When he got old enough to be left alone while John and Dean hunted, they might leave him on the couch and return hours later to find him in the same position. Sometimes the only indication he'd moved at all was that he had a different book in hand. Every town they stopped in for any amount of time, one of the first orders of business was to get Sammy a library card. The family's library card collection surpassed even its cache of fake IDs. And every time they left there was a clash over how many books Sam was allowed to carry along with him. At 5 he negotiated more book space for himself in the trunk by giving up a beloved teddy and the few other toys that he'd managed to collect over the years. John was probably sadder to see the toys go than anyone.
It was probably for the best, though, this ability to draw completely into himself. It probably served him well in the revolving assortment of school cafeterias where he didn't know anyone to sit with or talk to. And on all the nights he was left alone in the car while John and Dean swaggered into haunted houses. It certainly didn't hurt his grades. 'Who would have thought,' John wondered, 'that a son of mine would ever make straight A's?'
It was rough on Dean though.
Where Sammy was stillness, Dean was constant motion. A blur. A force of nature. Dean was a fussy baby, never happy unless he was being bounced or rocked or walked or driven. And the term toddler was absurdly accurate – as were the terms terrible twos and terrible threes. Fearsome fours and fives would also have worked well. Or fearless, depending on whose point of view you were describing. The words "no, no, no" rang through the house for what seemed like years.
At 4, he was disappointed when the baby brother he'd been so excited about turned out not to be a ready-made partner in crime. He seemed to believe them, though, when Mary and John promised him Sam would be more fun when he got older. And in many ways it was true. Sam worshiped his big brother and was always glad to be invited to smash plastic cars together or play dead Indian to Dean's victorious cowboy. But left alone for long, and he would wander back to his books – and that was a place Dean couldn't follow.
Every now and then, Dean would try. "Whatcha readin', Sammy?" he'd say. And then – after shaking Sam out of his trance, repeating the question and listening to the long, complicated explanation – "That sounds pretty good. Maybe I'd like it?" Sam would gamely hand over the book (he was probably reading three or four others as well, anyway), and Dean would settle down at the other end of the couch.
He'd get a few pages into the book, though, and his attention would wander. His foot would start bouncing impatiently up and down. He'd drag his eye back to the page, read a few lines and then laugh out loud. "Ha, listen to this, Sam," he say, and proceed to read a few interesting lines, ignoring or forgetting the fact that Sam had certainly already read it for himself. Sam might look up – if it happened soon enough that he hadn't fallen completely under the spell of the new book – and smile encouragingly at his brother. But it was a bone to a dog. For Sam reading was a solitary pastime. And Dean didn't do solitary.
John didn't know of any of the books that Dean had actually finished.