Spencer was, for once, struggling to keep up.
The Doctor had laid out 'a few of the simpler equations' for him and was now tossing out variables at sporadic intervals while his fingers moved with incredible speed over the keyboard. Presumably, he was doing the more complicated calculations in his head as he did so – and, at the same time, he was chatting easily with the technical analyst whose office they had invaded. She had looked quite irritated when they swept in an hour ago, but now she was flipping her hair and giggling girlishly at some joke of the Doctor's. Spencer, meanwhile, was entirely focused on returning accurate values when the Doctor asked for them.
He would have probably been envious of the Doctor's ability to instantly ingratiate himself into his surroundings if he hadn't recognized it for what it was – the survival mechanism of a man who constantly relied on the acceptance of strangers. The Doctor had to make it seem like he belonged everywhere, because he didn't really belong anywhere.
There was a lull in the string of numbers, and Spencer's attention turned to the conversation which he previously hadn't had the spare brainpower to register.
"Oh my gosh, listen to you!" the technical analyst was exclaiming. "You are such a geek!"
"That I am," agreed the Doctor, ducking his head with false embarrassment. Or was it false? It was hard to tell what was real with the Doctor – he was like an optical illusion, shifting in impossible ways every time Spencer turned his head.
"Don't tell those guys," said the technical analyst, rolling her eyes and jerking her head towards the door, indicating UNIT's military personnel. "It will break their little macho hearts. They're all convinced that you're secretly some sort of action hero – god forbid that someone save the world just by being intelligent."
Something clicked in Spencer's brain.
"That's it!" he exclaimed.
"What?" questioned the Doctor, looking just as lost as everyone else did when Spencer spoke without explaining himself, but Spencer wasn't listening. He scrambled for the door, nearly tripping over his own feet in his hurry.
"He's not a soldier!" he said excitedly as he burst into the main room, the Doctor at his heels. "The unsub – he works for UNIT, that's how he got the records, but he's not a soldier."
There was a pause as everyone turned to stare at him, wearing nearly identical looks of incomprehension.
"Oh," the Doctor breathed from behind him, understanding. "He turned around."
"Exactly!"
"Wait, what?" questioned Morgan.
"Reid, explain," ordered Hotch.
"That reptilian alien –"
The Doctor made a sound which was presumably the alien's real name. Spencer didn't bother trying to replicate it.
"—he was in the middle of cooking his dinner; halfway through chopping an onion. Why would he have turned around?"
"Because he heard the unsub coming . . . and a soldier would have walked more stealthily," Prentiss said slowly, comprehension dawning on her face.
"Much more stealthily," the Doctor agreed. "That species has terrible hearing – they rely primarily on scent, and that would have been completely obscured by the onion."
"Alright, so he's a scientist or a technician of some sort," said Hotch. "That narrows it down."
"Not enough," said Captain Stewart with a negative shake of her head. "We have hundreds of people working here; almost half of them don't have military training."
"That's what the rest of the profile is for. We should be ready to present it fairly soon. Doctor, what progress have you made on those signals?"
"Oh, I'm done," said the Doctor cheerfully, rocking back on his heels. "The planet's safe – well, as safe as it ever is – and it should be a good, oh, six, seven hours before the U'ulau can get his ship off the ground."
"Good," was all Hotch said, but Spencer could see from the tension in his jaw that he would have liked longer. Even assuming that someone recognized the profile right away, they still had to track the unsub down, organize an assault team, travel to his location . . . six hours was enough time, if everything went according to plan; it even left some room for error, but not much.
Hopefully, everything would go smoothly.
-BAU-
Dave let the others present the profile, keeping his attention on the Doctor.
"The man we're looking for is a member of UNIT, but not of the armed forces. He has a criminal record, but given that he works here, it's probably been expunged."
To the alien's credit, he didn't seem to resent no longer being the center of attention. His magnetic quality wasn't something he exploited or worked at; he hardly even seemed aware of it. He also seemed genuinely interested in what the team was saying.
"The hours of the attacks mean that he has either recently quit or been fired, or, more likely, that he works some kind of night shift."
"You keep saying 'he,'" Captain Stewart interjected. "How do you know it's a man?"
"One of the latest victims was a child," explained Prentiss. "An alien one, but still humanoid enough to invoke maternal instincts. While it's not unheard of for women to kill children, it's usually a specific delusion or obsession which drives them to it. With this sort of task-oriented killing, women will almost always show mercy to children, if only to the extent of treating their bodies more respectfully after death. There was no evidence of that here."
There was a shift in the Doctor's expression as Prentiss spoke of the dead child, a hardening of his face and darkening of his eyes. Dave recalled how he had acted before the child was killed – casual and charming, interested in catching the killer but perfectly willing to take his time about it. Afterwards, though . . . .
Dave generally viewed intense anger as a sign of weakness. It meant that you weren't thinking straight; made you more likely to make mistakes. It was good in an unsub; bad in an agent; very bad in a leader. The Doctor had certainly shown touches of that rage, personal and pain-filled, when he had learned of the Archangel Network's continued existence, at it had been terrifying.
His cold, controlled fury at the mere mention of the dead child was worse.
"It's important to remember that while the human who is physically committing these crimes is working in collaboration with an alien entity, he is not being controlled. Most likely he has suffered some recent loss or trauma that has caused him to lose faith in humanity, to the point where apocalyptic destruction is actually appealing to him."
"He could believe that humanity is irredeemably corrupted and needs to be put down, or even that he's doing the world a favor by putting it out of its misery."
The Doctor's eyes flickered away and down; a universal expression of shame. Perhaps he had had similar thoughts himself – about Earth, or his own planet, or maybe simply himself. The fragments of stories which Dave had heard had hinted at deep self-loathing beneath his arrogance.
"This man works here. Someone knows him. Think about anyone who's been acting oddly lately – not finishing their work, drifting off, seeming distracted or irritable. Especially concentrate on anyone who's undergone some sort of tragedy recently."
"Peter Thompson!"
Every head turned to the source of the voice, a plain, middle-aged woman in a lab coat.
"Sorry," she said, blushing. "It's just, Thompson – he's one of my lab assistants. He's been sloppy in the past few weeks, distant. I thought it was just stress . . . his wife committed suicide a couple months ago."
Everyone surged into action. Aaron barked for Thompson's personnel file; a technician, anticipating, already had it up on the screen; Stewart was calling for a team to be put together; the Doctor . . . .
The Doctor was pulling on his coat. He was expecting to go with them, Dave realized. Of course he was; he was used to being in the thick of things, but Aaron would put a stop to that quickly enough –
Except that he wasn't. Aaron was actually encouraging the Doctor, pulling him into the discussion of the most effective way to talk to the unsub.
"Doctor, we'll need you to try and communicate with the alien. You probably understand its psychology best. Meanwhile, we'll try to divide and conquer – we might not be able to restore Thompson's faith in humanity, but if we can shake his trust in the alien, we can get him to surrender."
"I suppose you'll all be pointing guns at him," said the Doctor with a grimace of distaste.
"If he's armed, yes," said replied Aaron shortly.
"You won't be carrying one?" Prentiss questioned.
"Never," answered the Doctor with feeling.
"Aaron, a word?" Dave interjected, steering the younger man away from the group and to the edge of the room, where it was slightly quieter.
"Yes?" asked Aaron.
"Are you insane?" said Dave sharply. "You can't possibly be thinking of letting that guy out in the field."
"I'm not in charge of this investigation, Dave. It's not my decision."
"Then talk to Stewart. She respects you; she'll listen to your opinion."
"She's not in charge either."
He was right, of course. The Doctor had been calling the shots from the instant he turned up. UNIT worshipped the ground he walked on. Still . . . .
"He's more unsub than cop, Aaron." There was a thin line between hero and villain, and an even thinner one between vigilante and psychopath. All those stories of the Doctor defeating alien foes – it didn't matter that they had been monsters to the humans; they had been people to him. And he had slaughtered them. Dozens, hundreds, again and again. Justified or not, it took a certain type of person to be capable that.
"I'm aware of that, Dave, but that doesn't make him a bad person, and it certainly doesn't make him an incompetent one."
Aaron's gaze turned back to the team, but not to the Doctor – instead, it fixed on Reid. Brilliant, damaged Reid, from a broken home with a family history of mental illness, who had been known to act recklessly and even self-destructively, and who even Dave had to admit was one of the best damn agents they had.
"Okay, I get your point."
And he did.
That didn't mean he had to like it.
-BAU-
Derek wasn't sure how he had ended up in a car with the Doctor. It may have been Hotch's design, or a spiteful move of Rossi's, or some unfathomable scheme of the Doctor's, or even a total coincidence, but there was some shortage of official SUVs and he found himself alone in a sedan with an alien and a broken radio.
Said alien was humming. He was humming 'Another One Bites the Dust.' He was humming it very enthusiastically, and very slightly off-key.
"Look, could you not do that?" Derek snapped at last.
"What? Oh, yes. Sorry."
He fell silent . . .
. . . for approximately two seconds, and then his fingers began tapping irregularly against his leg.
The man was like a five-year-old. A smart five-year-old, who got bored after three minutes of inactivity and began experimenting with household chemicals.
Tap. Tap. Tap-tap. Tap-tap-tap. Tap-tap-tap-tap-tap. Tap-tap-tap-tap-tap-tap-tap-tap-tap.
There was nothing for it. Derek would have to strike up a conversation, lest the Doctor start pulling apart the dashboard.
"Why do you hate guns so much?" he asked, because he honestly wanted to know the answer and because it was less rude than 'who the hell are you?'
The Doctor stilled abruptly, his resemblance to a hyperactive child evaporating like mist.
"Because their only purpose is to kill," he stated – truthfully, as far as Derek could tell, but also carefully, watching Derek's reaction out of the corner of his eye.
"Fair enough," Derek conceded, and the Doctor relaxed marginally. "But seriously, in nine hundred years you've never –"
He had been about to say 'killed anyone,' but the Doctor shot him a sharp, warning look and he changed direction mid-sentence.
"—carried a gun?"
"Not as a general matter, no."
"But you've used one," said Derek, and it wasn't really a question.
"We-ell, that depends on your definition. I've bluffed with one, certainly. Shot a lock, once. Used to be pretty handy at disabling Dalek eyestalks, before they got those bloody force-fields –"
"Have you ever shot at a living person?" Derek interrupted. Somewhere in the back of his mind he was aware that there was no real reason for him to press the issue, that this was one part idle curiosity and three parts power play – but it would be another twenty minutes before they reached Thompson's house, and anything was better than listening to the Doctor attempt to reproduce 80's rock songs.
"Sentient being? Yes. Person? Like I said." The Doctor's hand clenched on the arm of his seat. "Depends on your definition."
There was a definite edge in his voice, cold and ominous, like the creaking of thin ice.
Derek fell silent.
This time, it was a good ten seconds before the Doctor started humming again.
-BAU-
Emily was slightly surprised at Thompson's house, a rather endearing little cottage at the end of a long drive. It was dark and silent, and she would have thought it empty if not for UNIT's infrared cameras which assured them that Thompson was there. She was also slightly surprised when both Morgan and the Doctor arrived in one piece, the sedan screeching to a halt among the tangle of official vehicles which had formed about ten yards from the house.
She was not at all surprised by the irritated scowl on Morgan's face as he climbed out of the driver's seat, slamming the door behind him.
"No alien should know that many 80's rock ballads," he complained as he accepted a bulletproof vest from her and pulled it on. "Nobody should know that many 80's rock ballads."
"And you thought Reid was bad," she teased, and turned around – just in time to catch the affronted look on Reid's face as she almost ran into him. "No offense, Reid."
"Quite a lot taken," he muttered as he stepped around her, not meeting her eyes. She winced internally. She'd have to remember to make it up to him later.
She grabbed an extra vest and moved towards the Doctor, who was standing away from the group, surveying the house with lowered brows. He didn't seem to notice her approach.
"Here," she said. He glanced at her, then at the vest she held out to him.
"No, thank you," he said lightly, turning his gaze back to the house.
"Don't be an idiot," said Emily, rolling her eyes. "Just because you're not carrying a gun doesn't mean that he isn't."
The Doctor snorted.
"He's working with a Phantom Assassin. I highly doubt that any gun he has will be stopped by Kevlar."
"Okay, you're probably right, but it can't hurt to wear it anyway."
"I'd really rather not, thanks." His smile was polite, but it held none of the warmth from earlier. She backed off, squashing an irrational twinge of hurt.
"Your funeral," she muttered as she rejoined the milling crowd of law enforcement. If he heard her, he gave no sign.
"Looks like Thompson's in the basement," Stewart was saying, looking at some high-tech device. "He's alone, so there won't be any civilians in the way. If he doesn't answer the door we go in hard and fast, agreed?"
"Agreed," Hotch confirmed. "My team will take the lead, if that's acceptable to you."
"You're the experts," Stewart conceded. "You and the Doctor."
"Speaking of whom . . ." Rossi said under his breath. "Doctor!" he called to the man who was still frowning contemplatively at the house.
"Yes, one moment," the Doctor called back absently. Everyone turned to watch him as he reached out in front of him, as if testing for an invisible wall – and apparently found one, because he gave a strangled sound and stumbled backwards.
"Doctor!" Jordan exclaimed with alarm, starting forward.
"No, stay back!" the Doctor ordered sharply, straightening again and holding up a hand in warning. "I'm fine," he added, in milder tones. "It's just a psychic shield. It's to be expected, really – the U'ulau are empathic, after all."
"Can you disable it?" questioned Stewart.
"Well, I can turn it off, but I can't risk doing anything more permanent without seeing the machinery. Psychic shields can get a bit nasty if you muck with the wrong thing. There won't be anything to stop Thompson from switching it back on once he or his hitchhiking friend figures out that it's off."
"And then what would happen?"
"To you lot? Not much," said the Doctor with a sniff. "It looks like it's programmed to stir up negative emotions – pretty basic stuff; he probably picked it up along with his cloaking device. There's a species on Regulus III which uses something similar as a defense mechanism. None of you are very psi-sensitive, and since you'd know what was going on you'd be able to recognize it as artificial and shake it off fairly quickly. It would be a bit unpleasant, but it wouldn't do any lasting damage."
"And what would happen to you?" asked Hotch, reading what was omitted from the explanation.
"I'm not entirely sure," the Doctor stated lightly. "Still, there's no avoiding it – I can't very well stay out here. He could start threatening you with a toaster and you'd be none the wiser."
"He's got a point, Hotch," said Morgan. "We have no idea what we're dealing with. If he's willing risk it, I say we let him."
"Captain Stewart?" said Hotch, ceding authority to the UNIT officer, who presumably knew the Doctor better than they did – or at least knew more about him.
"I trust your judgment, Doctor," she said, meeting the alien's eyes. "But you two stay out here," she added, turning to the two other UNIT members who had accompanied her. "Monitor the situation. Call for backup at the first sign of trouble."
"Yes, Ma'am."
"Agent Hotchner, your lead."
"Thank you. Doctor, you're unarmed; I need you to stay behind us. Agent Rossi, Agent Todd, cover the back once the shield is off. Everyone else with me. Doctor."
The Doctor pulled out his sonic screwdriver and a high-pitched buzzing filled the air. In the gathering dusk, the blue light of the device cast his sharp features into harsh relief and reflected off his dark eyes, making them glow eerily.
Emily shivered.
"Yes, hang on, one moment, I just need to find the frequency – there."
There was no perceptible change, but a tension which Emily hadn't even noticed eased from the Doctor's shoulders.
They fell automatically into formation as they moved forward, barely even needing the directive gestures which Hotch gave them. From her position in the back Emily had a good view of all of them: Dave and Jordan, as they disappeared to the back of the house; Hotch, grim-faced and professional; Morgan, in his element; Reid, awkward but determined; Stewart, easily falling in behind Morgan; and finally the Doctor, looking like a specter with his pale skin and incongruous attire, out of place and out of time.
Hotch rapped on the door.