They had pulled Adam out of Hell, taking it upon themselves to do so after Sam and Dean just…left him there. Ever since then, he’s been eternally grateful to them and has lead a much happier life, being away from hunting and all the Winchester bullshit.

He’s found a home with them and over time, realized he’s fallen in love with them. Not only did they save his life, they’re also his best friend. He’d feel lost without them.