Sam going away with his brother of a spontaneous hunting trip to find their father was.. surprising. at the least.
Sam never spoke to his brother, not after having left for Stanford. he told her all about it, about how weird their family was and how they moved from motel to motel, city to city.
then he dropped the bomb on why it happened. his family— hunters. hunting demons and vampires and wendigos. fairytale monster characters.
after he got back, a yellow-eyed man strung you up on the ceiling, but, thankfully, Sam and Dean got back in time to shoot it before it could cut into your stomach and burst you into flames.
but, Sam still wanted to hunt with his brother, to get his father back, mend the relationship with his brother.. but with you by his side. not wanting anything to happen to you.
so there you are, in the backseat of the Impala his father passed down to Dean, riding off to god knows where.