"Oh shit, what do I tell Dean?" was all that could go through Sam's mind. He kept thinking that exact thought, plus a ton more curses, as he looked at the…the… well what definitely is not the impala. Dean was off, trying to find and meet with Crowley, but Sam was sure he was just goofing off at some bar; meanwhile Sam was on a hunt, with the impala. After blinking a few times, and walking away and coming back, he couldn't make sense out of what he was seeing. All he was a big black box. How do I tell Dean his…baby… (Sam cringes at calling the car 'baby') is now a black TARDIS? Yes, Sam is a whovian, but there is no way he could let his brother know that. Once, Dean went out and came back to see Sam watching Doctor Who. Dean was about to laugh and mock Sam, when Sam quickly changed the channel, claiming to look for something else to watch instead. Maybe Dean took the impala and I didn't know? That was plausible, and Sam was more than happy to accept it, until he noticed his and Dean's initials in the door (which Sam remembers carving), the little green army man in the window (which he remembers playing with in the car as a child), and the same Kansas KAZ2Y5 license plate on the top. Sam wasn't sure if he should be relieved because he hadn't lost the car, or more concerned because it had suddenly been morphed into a fictional time machine. Aliens aren't real. And if aliens, let alone timelords were real, Sam would know. He would want to be a companion! If he was a companion, he could finally do something, which in his mind, was better than something Dean had ever done. How much more awesome would it be to say 'I stopped an alien invasion from taking over and destroying Earth' than 'I killed a vampire'? Much, much better he thought. "Well since this is definitely mine, well technically Dean's, I guess I ought to check it out." And that was when he opened the door.