Title: Parallel Lines

Rating: PG

Summary: Ten II and Rose meet again, after twenty-three years.

Warnings: Angst treated unsympathetically by the Author, allusions to Anthony Trollope and George Eliot, terrible physics jokes.

A/N: This is dedicated to my astrophysics professor, who seemed to have a great desire for the aliens to come and take him away, and for my fellow students, who were rather more inappropriate than shown here.

* * *

Most of his students think he's gay.

There are many reasons for this, and they gossip about them after class, in the hallways and outside on the pavements between the campus buildings. There are some that don't think he's gay, but they all agree that what he needs, most of all, is to get laid.

And for some reason when he overhears them discussing this they seem to be utilizing the material from his lectures well, if creatively. "I'm sure he chats up whoever he likes with something like, 'You call it ménage à trois, I call it gravitational lensing'," says Tony, in tones normally reserved for the lewdest of comments. Tony sits at the front of his class. The Doctor looks forward to seeing what Tony has to say about gravitational lensing on the next exam, and makes a note to himself to include a question on it.

The university is rather a small one, which the Doctor does sort of like, but gossip does tend to spread everywhere, and the teachers are just as bad as the students. "I've never seen him with a woman," a biology professor says to another. "D'you think he's got a hidden boyfriend somewhere? It's not like anybody cares, these days."

The Donna comments that the Doctor can't control, about fashion or gossip, he knows cause more Really I'm Not Homophobic nods in his direction, and a few men asking him out. He turns them all down. Even though some were very nice and cute about it, and had nice bums—no, wait, that's Donna again.

He hasn't gone out with anyone since Rose. He doesn't mind; he accumulates all sorts of friends who later say things like "I mean, he's not flaky, exactly, it's just.... oh, I don't know." And every year on what he tends to call his birthday Rose sends him a card. Hope you're doing well, it always says. It doesn't say, Glad to see you're another year older, because at least she knows that would mean, Glad you're another human milestone closer to a death you never expected. It doesn't say, I'll come visit you soon, because they both know how she feels; how she can't look him in the face and not see the other one. The real one. She finally decided that her reward for finding her Doctor again wouldn't be to take on the responsibility of dealing with what he had become.

When the Doctor looked in the mirror this morning, he saw all the other faces he had in the centuries of his past, and that now, there was something new. A tired-looking man, lines deepening on his face. A few little scars from the times he'd tried to grow a moustache, for variety's sake, and then hacked the whole thing off when he realized that it didn't change a thing. Little remains of his brown hair; some sort of wiry black and white stuff has grown in, in its place, and he doesn't know what to do with them- he hears there is dye for situations like this, but he has no one too impress and he doesn't want to go back to looking like he once did. He never wears brown suits anymore, either, but sometimes he does dress in a jumper and a black leather jacket.

He has times where he's more Donna than Doctor. It helps especially when he's grading papers, when he's writing articles, anything with detail. Over centuries he had learned to see details, but she was the one who could pick out a questionable word in a company letter and made sure to print the correct copy on letterhead and who knew about things like cause and effect. He'd never seen time as a sequence of causes and effects, so being half Donna was a godsend in departmental meetings.

He needs to focus on finishing reviewing this article on quantum mechanical pressure, but it's difficult when he knows how quantum mechanical pressure works better than anyone on this tiny planet (and particularly this person who sent him such a pleading email for a preliminary peer review,) and undergraduates are chattering about blonde biology professors right outside his office door. Do they mind?

There's a knock on his door and he fumbles with his glasses. Honestly, he can't take much more of this distraction, and if it's a student.... once upon a time, he destroyed entire species, and he knows now that he still isn't beyond failing someone for being a persistent ass.

"Come in," he says, finally removing the glasses.

"I just heard a great chat-up line out in the hall." He hears the voice before she enters. "I hope you haven't been using it on your students, though. I know large age gaps have never bothered you, but the administration may take a dim view of it."

"What was it?" he asks, trying to make sure his voice is steady. Her head is tilted to the side as she pokes it through the widening crack in the door, making a spill of light hair the first thing he sees. Lighter than he remembers it; he notes that she couldn't keep all the white from her hair even with dye. Then he sees her eyes, and but for all the crow's feet decorating their corners, she might have been seventeen again. She's as beautiful as ever, perhaps more so.

"If I remember correctly, 'In a curved universe, even parallel lines eventually converge.' Is that one particularly effective at bars? Or do you avoid those?"

"I try to, yes," he answers, wondering if he should be looking at her, if she'll take that as a step too far. He glances down at all the piles of paperwork on his desk, then back up. He doesn't want her to think she's not welcome, only she sort of isn't. He forgave her a long time ago, but it doesn't mean...

He doesn't know what it doesn't mean. He doesn't know a lot of things, quantum mechanics aside. He didn't know how to sign a lease on a flat when he first began to live here. He didn't know what qualifications he needed to earn the name Doctor. Rose could have helped, if she had wanted.

"You look different. Older," she says softly. "It's been a long time."

"I'm twenty-three now." He laughs humorlessly. "I have students, young students, who were born after I was." Clearing his throat, he shifts a pile of tests onto a pile of labs penciled on graph paper. "I suppose it's the Donna side talking, but I have to fight the urge to buy a bottle of red hair dye and get rid of the greys."

Rose presses her lips together, and the Doctor knows that mentioning Donna was the wrong thing to say. Donna was one of the reasons Rose had pushed him away. He had wondered so many times if he should have told her about Donna, about Jack, about the Racnoss and about Martha and the Family and all of it.

"Yes. Donna." Rose looks away, and walks over to his bookshelf, studying the spines. He knows what she'll see, Brian Greene and Newton and a whimsical little book of stories called Einstein Dreams. He has the complete Sherlock Holmes there, too, and Rudyard Kipling's Kim, and some books on literary theory, and economics, and geography. They gave him a large office, but there is only so much he can do with it. He never got the hang of living in a space that wasn't the TARDIS.

He should never have mentioned Donna, and says so. "And for everything- oh, forget it. I'm sorry, Rose. I'm always so sorry. What..." He sighs as if twenty-three years had somehow been longer than eternity. "What are you doing here?"

"I just- I came to see you. I never have. I've never seen what you made of yourself, without me. I never did what the first Doctor said, to take care of you, and I needed to see if you had- what you had done with yourself."

"I got a degree. I got another degree. I got a flat and an office and several classes and my very own computer and several publications and I'm thinking about trying to win the Nobel Prize. I think I've managed not to get anyone killed, even though I've heard that the psychological damage my exams inflict is permanent."

"You've done well for yourself, then," she says hesitantly.

"I have." No thanks to you, they both hear, and now she winces.

"You were the one that walked away. Over, and over again, Doctor. On the beach, twice."

"That was him. I stayed. I had to stay."

"You didn't have to stay the next time. And you didn't have to leave."

The Doctor sees a flash of color go by outside, in the hallway. "Rose, close the door. Sit down." Maybe she has found some glimmer of the respect she once held for him, maybe he's said it too much in his teacher voice, but she does as he says. He wonders if he should have taught students for twenty years before even attempting to tell her not to wander off. It still probably wouldn't have done any good. "I left because you would never see me. You would only see him. And so you would never even look at me."

She admits that this is not untrue.

"He abandoned us here. He abandoned Jack on the Gamestation. He took Donna's memories away from her and I know how much she pleaded with him to stop, because I am her. He gave his enemies a second chance but no more, and he never even gave you a first chance to come back to that universe."

"Stop it," she grates out. He's being cruel, he realizes. There was no need to dredge up everything they said before. He had long ago thought to never see affection in her face again, and reacting as if he expected it was immature of him.

"It's been a long time, Rose. Even I think it's been a long time."

She lays her hands on her lap, stares down at them. "I knew about Gallifrey. He never said, but I pieced it together after awhile, after the Gamestation and what he was trying to do. It was horrible, but as long as he was with me I didn't care, because I knew he was real and I never knew Gallifrey. But I knew Jack. I knew Donna, how brave she was for this Doctor that she had never met, in that world. He could have done something, if he had looked hard enough for an answer. But all he would ever do was set the fuse and run."

"Yes," the Doctor says.

"That's why I came. To see if you had a different face-"

"Rose, I can't regenerate any more-"

"I know that." She flashes him a quick smile and it makes him want to laugh and his chest constricts simultaneously. "But you do. You're not him anymore. Maybe you were born in blood and war or whatever he said, but you're here. You're still here."

"There's no fuse to light, no place to run," he reminds her. "There's just me, and there's nothing special about that, anymore."

She stands, and comes over to his side of the desk. He doesn't dare look up at her until he feels her hand on his shoulder, and she says, "Look up, Doctor."

He raises his eyes to hers with a little start, for only a moment, and looks at her grey suit, her resigned face, all saying, I know. I know what happened. I know what you're doing now. She leans over to rest her head on top of his, her hair spilling over his face like a veil to hide him, and then he knows why she has come, even if she can't bear to fully say it; to speak of the shame she bears with him, or of the acts which brought it down upon them. His confessions, finally, are silent, not desperate and grasping for understanding, and her promise to return to his side is silent. Brave and bold as she always was, she still shrinks from discovering how many atrocities he actually committed, and can't ask how much is the product of his taking responsibility for more than anyone ever could. And he does not say, I am innocent.

"Can we just start again, the way we live now?" she murmurs. "We never lived in straight lines, before. For all the times you- he- walked away, there were so many more where the universe wasn't enough to come between us."

"There are some theories that explain the universe as curved space," he responds. "The data for expansion theory doesn't completely conform to a flat universe. Parallel lines can still converge. If they align with the right curves."

"Good," she says. "Glad to hear it." She pauses. "…And those rumors I heard in the hall, about gravitational lensing…?"

"Completely untrue," he assures her. "As is the one about clothing falling faster than 9.8 meters per second squared. Can you stay?"

"No," she says, stepping back, and reaching for her purse. "I have a meeting in a while, and then I have to drive back to London this afternoon. But I'll come back for you."

"Good," he says.

As Rose opens the door, they both hear the end of a discussion. "-know what black holes and women like that have in common, right? Undeniably attractive, and astrophysicists never get to see them."

"Then what's she doing in his office, then, with the door locked?"

The Doctor flashes a grin at Rose. "If I was your derivative I could lie tangent-"

"Too soon," she says, but she grins back anyway, at this suggestion of a future, and steps outside.

"Don't drink and derive!" he calls after her, then settles back into his chair, and decides to call his friend and explain how a unified theory of quantum mechanics actually works.