A/N: I stumbled upon a Doom/Star Trek 09 crossover and was immediately fascinated by the idea of an immortal Doctor McCoy. So I went and checked out the Doom movie. Can I just say that Karl Urban is a lot hotter than I thought? It's amazing what make up and character changes can do for an actor.

After reading several fics a few things grabbed my attention. So thank you to:

Miss_M_Cricket for the title, and Reaper's instinctive knowledge and the anon poster over at st_xi_kink: part 13 for the adoptable plot bunny that I've rewritten as this first chapter.

Disclaimer: I own nothing of Star Trek in any of its forms or Doom.


M class planet just outside of Federation space – 1 year post Vulcan's destruction, 213 years post Olduvai

As the large alien did his best to beat the life out of Doctor Leonard McCoy, his mind was elsewhere. It wasn't that he didn't feel the pain, he did, but the pain and the danger that he was in was in fact, nothing new to him. It was hardly the first time he'd had his life threatened or the first time someone had tried to kill him, and he couldn't tell the man about his non-existent slaver boss anyway. He was far more concerned about a letter his sister had recently sent him, one telling him about his five year old daughter.

Jo-Anna McCoy lived in Georgia, on Earth with her mother. She and McCoy had had a whirlwind romance and marriage, which ended in divorce just six years later. Most of the people he had known had discouraged his marriage to Jocelyn, mostly because they were both residents at the time. They knew that the odds of the marriage lasting through the stresses of one of them being a medical resident was unlikely, both of them being residents at the same hospital did not improve them.

McCoy had never told his now ex-wife about his sister, something that he was later grateful for. Samantha had moved to Georgia specifically to watch over her niece and make sure that her brother knew what was happening with his daughter. Spying it might have been, but McCoy was eager for the slightest news of his little girl. Focusing on the letter he never saw the blow that crushed his skull.

Grunting in disgust that he hadn't been able to make the weakling talk, the alien picked up the body and took it down to the cell where the other two men were being held. Throwing the body on the floor of the cell and taunting the chained up prisoners made him feel a little better, so he left them to contemplate their comrade's body while he got a meal and a drink. Knowing what was waiting for them would soften them up a bit before he returned to his work.

John Grimm woke instantly, searching for trouble before his eyes even opened. It was a habit that had kept him alive for a long time and he had never had any intention of circumventing it. He was lying on cold dirt floor in a pool of his own blood. At least he thought it was his own blood, as he could feel the cool stickiness of coagulating blood on his skin. He didn't feel any pain but that was nothing new. He healed so quickly that he only had time to feel it for a brief moment before he fully healed.

There were two men talking above John. For half a second he could almost believe that he was hearing Duke threatening to rip someone in half, but his team was long dead and gone. At least whoever was talking seemed to be upset on his behalf. He'd better let them know that he was alive and kicking. "Don't bother on my account," he said as he rolled over. The two men were chained to the wall right above John. The one on the left was Human, blond and blue eyed while the one on the right was a Vulcan, pale and dark. Both had been beaten.

"BONES! You're ok! I thought they'd killed you!" the young Human man said.

He couldn't have been much older than The Kid when he'd died. John shook the memory away with the ease of years of practice. "Don't know any Bones, my name is John Grimm. You can call me Reaper." He stretched as he stood, covertly checking his physical status. He'd been hurt badly. He could tell both by the amount of blood on his clothes and the tightness of his newly healed muscles. He was wearing a plain pullover shirt and pants, both of which were brown and unmarked, similar to what the other two were wearing.

"So, who are you two?" John asked as he leaned against the opposite wall. The cell looked pretty primitive, no artificial light source and no cameras that he could see. There was a small window high up on the only unoccupied wall, barred with what looked like rebar. The last wall was made up of similar bars with a door that was hardly any sturdier. He should be able to get out when he wanted to.

"Fascinating," the Vulcan said, peering intently at John. "You resemble our Chief Medical Officer to an astounding degree." Spock had seen that the man's boots were of higher manufacture than this primitive world could produce, although he was dressed in the same sort of slave garb that he and the captain had been forced to change into earlier. It would be logical to conclude that this Human male had arrived from off planet at some point.

"We have to find him," the Human said, almost to himself. "I'm Captain James T. Kirk of the Federation starship Enterprise and this is Mr. Spock. He's my science officer." 'Great, officers,' Reaper grumbled to himself. Officers were rarely a good sign, especially ones that announced themselves with anything approaching their full name. Nothing of this showed on his face for Kirk or Spock to see. "We were investigating to see if this planet was ready for first contact. How about you?" He too had noticed Reaper's boots.

Reaper shrugged. He ran his fingers through his hair and wasn't surprised to find blood, although it was a lot longer than he remembered. He'd been hit in the head pretty hard. Short term memory loss was a common side effect to a head injury, so he wasn't too worried. "One minute I'm having a drink, the next I'm waking up here," he said. That much was true, but it also didn't give out any real information, like the fact that he couldn't actually get drunk and most drugs didn't work at all on him, or that he had no idea just how much time had lapsed from that drink to now. Just because he was thrown into the same cell as these guys didn't mean that they were allies.

"Then logically you must have fallen prey to the slavers who own this compound. Undoubtedly you have somehow angered these men as they would not wish to damage valuable merchandise. How badly are you injured?" Spock asked.

Reaper shrugged. He'd go with what had worked for him in the past with someone who didn't know him. "I'm not hurt at all. I'm humanoid, not Human. My species heals quickly." It would also help him later, because there was no way that a normal Human could get out of here the way he could, not that he was sure he was going to let these two live with the knowledge that he had even been here.

"That's good, but do you think you could get us loose?" Kirk asked, shaking the chains that Spock had seemingly forgotten in his investigative tangents. "Since you aren't Bones we need to go find where these creeps have him."

Reaper cocked his head. The kid was annoyed at both of them for going off track, but wasn't yelling or barking at either of them, a point in his favor. Most of the officers John had served under would have been foaming at the mouth by now wanting to be let loose and to get down to business. Plus, he was worried about his man, which was the mark of a good leader, something Sarge had been before he'd cracked on their last mission. In the end it was simply the fact that if there was any group that John truly detested besides unethical scientists it was slavers that made up his mind for him.

John had taken two steps towards Kirk and Spock when he suddenly froze and turned towards the cell door. A man walked up to the door, looking down and fiddling with the keys on his belt. His other hand held a solid projectile weapon. When he looked up and saw all three men in the cell alive and well, he squeaked and swung his gun up to point it at them. That was enough for Reaper. As Duke had said once so long ago to The Kid, "It's like this see….If it's trying to kill you, it's a threat." And a deadly threat was to be met with deadly force.

Reaper reached out quicker than anyone there could see, grabbed the end of the gun and pulled, slamming the guard into the bars of the cell. The guard dropped, leaving Reaper in possession of the gun. He finished pulling the gun into the cell, swung it over his shoulder and dropped down to the floor, reaching over to where the guard had dropped the keys.

Unfortunately they were just out of his reach. Rather than make a futile effort to get the keys, John turned to examining the door. It was only held shut with a simple bar and slot lock. He snorted under his breath at the shoddy lock. It wasn't like someone could open it with bare hands, but if he'd had even the simplest lock pick; it would have been child's play to get free. As it was, he simply kicked the lock, shattering it at the point where the bar went into the doorframe.

This of course rendered the lock useless and the door swung open with the remaining force of John's blow. He darted out of the cell and checked the guard. Unconscious, with a broken jaw, the man isn't going anywhere for a while, but John wasn't named Reaper by his team mates for nothing – he never left an enemy alive, well that and his last name. Like he'd once told his sister, his team mates had been Marines, not poets. He swiftly broke the man's neck, killing the guard instantly. It's as clean and painless a death as he could manage under the circumstances.

Reaper patted down the body, quickly confiscating the pistol, second set of keys and knives that he found. Too bad the guy hadn't been carrying a map. He turned back to the cell to find Kirk staring at him in shock and the Vulcan's eyebrows attempting to climb off his head. "You are definitely not Doctor McCoy."

It didn't bother Reaper that they hadn't believed him. He'd have reserved judgment too if the guy really looked as close as Spock had said he did. "Never leave a live enemy at your back kids. Nine times out of ten they'll attack you when you least expect it and it's a death sentence to any wounded you might have," he lectured as he unlocked their chains. He didn't dare pull the chains apart as their fragile wrists could easily be broken in the process.

"Your close resemblance to Doctor McCoy renders your actions quite disturbing. However, your logic is quite sound for an emotional sentient," Spock told Reaper.

Reaper shrugged again. He was doing that a lot around these two. From what he remembered about Vulcans he thought that was a compliment. "I was a combat medic with a special forces team once upon a time. Like it or not, this is combat because I don't think that we're going to be able to just walk out of here, especially if your Doctor McCoy is in anywhere near the condition I was when I was thrown in here." The three of them looked grimly at each other before Reaper turned and led the way out of the cell, leading with his new gun just like he was on a mission with a couple of newbies.