When Canton meets the Doctor for the first time, his heart is, momentarily, caught in his throat, and before he can clear his mind and focus on the mission he thinks, Shit. Because this man is utterly insane, and Canton has always gone for the mad ones.
With the time travel and the space travel and the rest, he mostly puts it out of his mind.
When the FBI comes to call, Canton is in a bar drowning his sorrows. Which is funny, because that's exactly what he did after the FBI fired him.
Sometimes, Canton thinks the universe just doesn't like him very much.
He's in a bar drinking himself stupid because he's had a fight with his would-be-fiance, and because the 'would-be' is never going to go away, and because maybe all of it is going to go away. Canton doesn't know if he can do this anymore. He probably can, but James can't, and why--
That's about when he usually signals for another round.
This time, though, as his thoughts are spinning in the same pattern they've been in for the past hour, the FBI comes and whisks him away.
Fuck it. The universe clearly hates him.
When Canton is pretending to interrogate the Doctor, while really discussing the pros and cons of pretending to kill his friends in order to get the five of them together again, the Doctor abruptly stops talking about drugs that won't be invented for two hundred years and starts asking about Canton's personal life.
"So, Canton, when are you getting married?"
"I'm not," Canton says, because he isn't. Because he's been spending all his time on this and hasn't called James in ages, and also because he's realized, he can't give this up. He wants to get married, but he also wants to not spend his life getting drunk in bars. And he doesn't think there's a medium between those two things.
"Why? Because of the FBI?"
"Because of me."
And with that, they begin talking about logistics and escape plans again.
Before Rory Pond is shot but after River Song jumps off a building, Canton is still pretending to interrogate the Doctor. He's just glad the stupid prison is finished and so they can talk freely without him having to drag the Doctor to a room somewhere, and then alter the video recording to make lip-reading impossible. Going undercover is so much work sometimes.
"I'll be glad when this part is over," Canton says. "I'm sick of getting betrayed looks from your friends."
"Don't worry about it, it'll all get sorted out in the end."
"Canton. Are you sure the FBI is really what you want to do for the rest of your life?"
"You know," says Canton, "you really have attention span issues."
The Doctor shrugs. "Oh, transitions." He waves a hand dismissively. "Boring. And you're avoiding the question."
"Yes," says Canton. He leaves.
While they're waiting for the Doctor to stop arguing with the TARDIS and bring them all home, Amy asks Canton about his fiancé.
"So what's he like, then?" she asks. "This man you want to marry." She leans her elbows on her knees and looks up at him, and it occurs to Canton she is very young.
It also occurs to him that no one has ever asked him about James before, not like this. Not even the Doctor.
He's not really sure what to say.
"His name is James," he finally settles on. "He's always smiling, and he thinks there's a bright side to everything."
"Wow," says Amy. "Wonder how he puts up with a sourpuss like you."
Canton tips his head back towards the ceiling and starts to agree with her. And then he thinks that maybe he knows. "Probably the same reason I put up with an idiot like him."
After the Doctor drops him off in Nixon's office and he is, reluctantly, given his job back, Canton takes the very satisfying step of quitting.
In 1988, the Doctor stops by for a visit.
"Sorry," he says, adjusting his bow tie and looking around. Incongruously, he's wearing a tux. "I'm a bit early. I was looking for your wedding."
Canton just blinks at him.
"Right. Very early then."
He and James are on the outs again. Sometimes Canton worries that he's wasting his time, that it's never going to work out. "I'll have to remember to send you an invitation," he says, and then he starts writing an apology in his head.
"Well, while I'm here. How does an early wedding present sound?"
Apparently, in the Doctor's world, a trip to the moon is an appropriate wedding gift. And Canton may want to kiss him, just a little, after he takes the first step and remembers watching it on TV nineteen years ago, but Canton is beginning to think that maybe that's just how everyone feels when confronted with a madman. And anyway, he doesn't, because James is there, gaping like a fish, and Canton kisses him because he never said a word about the time travel or the space travel or the fact that they shouldn't be able to breathe right now. He believed him, without question, even all those years ago.
Canton smiles, because his boyfriend is crazier than the Doctor could ever hope to be, and he loves him and wants to marry him and he's going to get to, someday.
When Canton kisses James, this time in front of a roomful of people who cheer and clap and grin, the bored kids sitting at the back who would just like to eat now, please, are being entertained by a funny man in a top hat and tails. They hardly notice, except that the funny man looks up for a moment and smiles, before returning to their games.
When Canton meets the Doctor for the last time, he watches him die.
He watches the Doctor die, watches his body burn into nothing, and he doesn't believe for a second that the Doctor is going to stay dead.
He wanted to marry James, he wanted something completely impossible, and he did it. He wanted to marry him more than anything he'd ever wanted before, more than he'd wanted to get into the FBI and much more than he'd wanted to stay in the FBI. And right now, what he wants is to call the Doctor and to take James with him back to 1969, wants to find President Nixon and tell him about his wedding, wants to see the look on his face and be able to laugh, and laugh, and laugh.
Maybe he did just watch the Doctor die, but if all these years have taught Canton anything, it's this: nothing is ever impossible.