Title: The Last Thing on My Mind
By: angstytimelord
Pairing: Tenth Doctor/Spencer Reid
Fandom: Doctor Who/Criminal Minds
Rating: PG-13
Table: 5, sound_of_drums
Prompt: 19, Walk Away
Disclaimer: This is entirely a product of my own imagination, and I make no profit from it. I do not own the Tenth Doctor or Spencer Reid, unfortunately. Please do not sue.

***

Spencer paced back and forth across the floor of the Tardis' library, hands clenched together behind his back. He had no idea where the Doctor was, but he knew that the Time Lord was somewhere on the ship, and he wondered how long it would be before the other man found him.

Not that he was trying to hide, he told himself, casting a glance at the doorway of the room. But he'd felt that he wanted a bit of time to himself, and the Doctor had seemed to understand that need. He'd come to this room, feeling that he could relax here.

But instead of relaxing, he'd found himself getting more and more tense and wound up. All he could think about was the time when all this would come to an end, when the Doctor would take him back to Earth to pick up the threads of his life again.

As much as he loved his work with the BAU, he'd come to a definite conclusion -- that he didn't want to go back to his job, or to the planet he'd called home.

He wanted to stay here with the Doctor, to be the companion who chose to devote their life to the Time Lord. He might not know all the reasons that the Doctor's past companions had chosen to leave, but he was determined to be the one who didn't go.

What did he have to go back to, anyway? Yes, he had friends, and he enjoyed his job. But he couldn't make a life out of that, not after he'd been out here, and especially not after he'd fallen in love with the most amazing man he could ever hope to meet.

There was nothing on Earth that appealed to him any more. If he went back, he'd have to deal with the constant attempts Morgan made to get together with him -- and with his own unrequited love for Aaron Hotchner, a love that would never be returned.

Besides, he didn't feel that way any more. He still cared about Hotch, but as a friend, not as anything more. The Doctor had changed all that.

He'd fallen head over heels in love with the Time Lord. And he knew that the Doctor loved him, too -- the other man had said so, and Spencer was absolutely certain that the Doctor wouldn't say those three little words unless he meant them.

But the fact remained that he was human -- and that he couldn't be with the Doctor forever. The other man had never said that he would let Spencer stay with him for the rest of his life; what if he wasn't intended to be here for very long?

It would hurt more to leave the Doctor than anything else had ever hurt in his life. The torture that Tobias Hankel had put him through would be nothing compared to how it would tear him apart to turn and walk away from the man he loved.

Spencer sank down onto the couch, burying his face in his hands. What was he going to do if he was forced to walk away from the Doctor and all they'd shared?

He couldn't leave the Doctor. This man had saved him; if it wasn't for the Time Lord, he'd still be dealing with a drug addiction that he might not have been able to kick on his own. And sooner or later, his colleagues would have found out about it.

What would have happened then? They'd have stood by him, of course, and tried to help him -- but the fact remained that he would have come perilously close to losing his job. And probably would have lost it, if he was honest with himself.

The Doctor had kept all of that from happening. He'd taken the burden of helping Spencer detox onto himself, and he'd made sure that there was no recurrence. And because of him, Spencer knew that he would never backslide, no matter how much he might be tempted.

He wanted to make the Doctor proud of him, to be worthy of this man's love. He'd spend the rest of life proving that he was worthy, if he had to.

But what would he do if the Doctor told him that their time together was coming to an end? Would he be able to accept that, and to walk away from the Time Lord with his head held high and his dignity intact? Or would be he beg to be allowed to stay here?

Spencer bit down hard on his lower lip, trying to hold back tears. He shouldn't cry over this; after all, he didn't know for sure that it would even happen. But it was a frightening subject for him to contemplate; if he lost the Doctor, he would lose everything that most mattered to him.

Oh yes, he could go back to Earth, back to his friends, to his job, to an empty life that would hold no promise and no joy for him any longer. He'd never be able to forget the Doctor, never be able to love anyone else in the same way.

He couldn't walk away, even if he was told that he had to. And he couldn't watch the Doctor walk away from him. That would be the ultimate pain, one that he couldn't bear.

He hardly realized that the Doctor had entered the room until he felt the Time Lord's hand on his shoulder, heard that soft British accent in his ear. His head jerked upright, his eyes wide and startled as they focused on the man sitting beside him.

"Spencer, love, what's wrong?" the Doctor asked him, moving closer to him and squeezing his shoulder gently. "And don't tell me that there's nothing wrong. I could feel your unease all the way through the Tardis. She picks up on things like that, you know."

"She does?" Spencer blinked, looking around him at the walls of the room he was in. Sometimes it was so hard for him to accept the fact that the Tardis was a living, breathing being -- and that she cared about the Doctor as much as he did.

"Yes, she does," the Doctor said softly. "And I need to know what's worrying you, so that I can help you put it out of your mind."

There was no use trying to hide his thoughts from the Doctor; he'd learned that already. "I-I couldn't help thinking about what my life is going to be like when you want me to leave you and go back to Earth," he whispered, feeling the tears rising behind his eyes again.

The Doctor blinked, looking surprised at Spencer's words. "What would make you think that's going to happen?" he asked, his voice conveying his concern. "Spencer, I don't want you to leave. Did I do or say something to make you think that I did?"

Now it was Spencer's turn to blink; he'd been so sure that the Doctor would eventually expect him to go -- probably sooner rather than later -- that it hadn't occurred to him whether or not his lover might have a completely different view of the situation.

"I was sure you wouldn't want me to stay," he said, looking down at his hands clasped in his lap. "But I don't want to. Not now, and not ever."

"I'd never dream of asking you to go," the Doctor said softly, tilting Spencer's face up to his own and gazing into the young man's eyes. "That's the last thing on my mind, Spencer. I'd be lost without you. If you want to stay here forever -- you'd make me happier than I've ever been."

"That's good," Spencer told him, feeling his heart leap in his chest. "Because I couldn't walk away from you, Doctor. If either of us left -- it would have to be you. I'm not strong enough to put you out of my life, or out of my heart."

"I couldn't do that, either," the Doctor whispered, pulling Spencer into his arms and resting his head against his young lover's shoulder. "Believe me, love, you're stuck with me -- for as long as you want me, I'll be in your life. Nothing could make me walk away."

"There aren't any words for how happy that makes me," Spencer told him, pulling away slightly and taking the Time Lord's face in his hands. As their lips met, the only thought in his mind was that he'd just been guaranteed a very happy eternity.

***