While Leonard had focused on finally ending an old nightmare, he hadn't thought of the ramifications of his actions.

It took weeks to settle the Admiralty down, and poor Jim bore the brunt of their anger and disappointment. He was held responsible for the destruction of Olduvai, something that Leonard felt guilty about, and had been suspended while the investigation was underway. But with the facility being no more than a crater on the surface of Mars, there really wasn't any investigation going on. "Witch hunt" would have been a more precise term for it.

For his part, Leonard had been grilled for his actions against an 'unidentified life form.' Apparently, even in the face of death, he was supposed to utilize the Prime Directive, which he knew was complete bullshit. He made sure to tell that to the Council, and it earned him a suspension right beside Jim.

The things he did for the little brat.

"Bones," Jim said quietly one evening. They were lounging around on Jim's balcony, enjoying the sunset illuminating the Golden Gate Bridge, a cooler of Budweiser Classic on the floor between them. But however relaxed Leonard had been, all the zen he'd found in the peaceful atmosphere was immediately chased away by Jim's subdued tone. "I need to tell you something."

Tell him something? Not ask? Leonard relaxed a little. "I'm listening."

Jim sat up and reached for his bag—the one that he'd suddenly started bringing around since his suspension as captain of the Enterprise—and from it, he produced a glass vial. Leonard felt the breath get knocked out of his chest as he stared at the familiar label.

C-24.

"I've been lying to the Council." Jim placed the vial between his outstretched legs, staring down at it contemplatively. "I found this when we spread out to search the rooms. It was in the lab where you killed the mutant."

Yes, he remembered. Sam had unhooked a vial from the stand, leaving seven other vials in the lab.

"At first I got it so that you could take a look at it and tell me what C-24 was. But then you got all weird, then you killed the mutant and we were all freaked out. I completely forgot about it until after we made our preliminary report and Olduvai exploded."

"So why didn't you give it to me when you remembered it?" Leonard asked, wary of what Jim had been doing with C-24. God, he hoped the kid wasn't stupid enough to experiment with it.

Jim shrugged. "I don't know."

"So why bring this up now?" he bit out, frustrated at Jim but trying to remain indifferent. "Did you want me to test it?"

"I think you already know what it is," Jim responded slowly, making the heavy feeling in Leonard's gut grow. "I think…" He licked his lips and cleared his throat. "Bones, tell me. Talk to me."

"Jim…"

"I need to know what I'm protecting." His tone booked no argument, but there was regret in his eyes when he added, "I need to know what I'm protecting you from."

In retrospect, Leonard probably didn't handle the news of their exploration of Olduvai very well, and he knew he must've left enough clues thanks to his negative emotional state. Leonard also, in that moment, absolutely hated Jim's uncanny talent for piecing a puzzle together. Two hundred and thirteen years of keeping this secret, and a youngling had uncovered half of it in the space of a month.

If it were any other secret and happened to anyone else, Leonard would've been pretty impressed.

It also didn't escape his notice that Jim hadn't seemed to consider why he was protecting Leonard, as if it wasn't even something he had to consider. That was the cincher, really—the way Jim just did things for him for no other reason than because he cared about Leonard, because Leonard mattered to Jim.

"Kid," he sighed, resigned at the fact that he was actually going to tell Jim about it all, after more than two hundred years of carrying the secret on his own. "You really don't want to know."

"Maybe," Jim allowed. "But tell me anyway."

Leonard stared at his best friend, and really, Jim was the best person he'd ever had the pleasure of knowing. He wasn't an ignorant innocent who didn't know the dangers of the world and the space beyond it, but neither was he a tainted soul who couldn't see the good things in life. Jim was a child of space, born in the inky blackness in the midst of despair and destruction and death. He was also a contradiction of time—an old soul with a young body and an ageless passion that encompassed his entire being. Jim was Jim, and he was one of the handful of things in this world that Leonard wouldn't want to have missed out on.

Jim… He could handle it, Leonard knew. Jim could take the secret, and he would take it to his grave.

"You know me," Leonard began, and the young blond straightened up to give him his full attention. "I don't drink coffee, I eat a lot, and I only sleep six hours every day. I had a nasty divorce with a hell-bitch, and I have a stubborn jackass for a best friend. You know me."

Leonard exhaled heavily, looking away.

"But I wasn't born as Leonard McCoy. And I wasn't always a doctor."

Leonard left when Jim refused to speak or look at him. He'd clutched the C-24 tightly, giving Leonard no chance to take it away and destroy the damn vial. At least, not without forcing Jim to hand it over, thereby also irrevocably damaging his friendship with the young man.

He knew Jim wouldn't turn it in—knew his best friend well enough to see that Jim only needed some time to absorb the information given to him—so it wasn't that he feared Jim would hand the vial over to the Admiralty, but fear that Jim would do something heroically foolish, like inject it into his own body. He knew Jim was a good person, that he wouldn't turn even if C-24 entered his system, but the past two hundred years wasn't something Leonard should've lived through, and he wasn't going to let Jim curse himself like this.

Like him.

When Jim's name flashed up from his communicator four hours later, he stopped everything he was doing and felt his chest clench with relief.

"Don't leave," Jim's tinny but unmistakable voice said through the speaker.

("I can leave, if you want me to go," he'd offered after he was done talking and Jim had nothing to say.

Jim had only kept staring down at the vial in his hand.)

Leonard sighed, closing his eyes as the heaviness in his bones went away. "I won't." There was a chime at his door, and he could hear Jim gasping for air past the metal surface. Leonard dropped the communicator and opened the door, and Jim immediately glanced around the room, his eyes taking in the packed bag on the bed.

"Don't leave," he said again, his tone full of demanding petulance as he clutched at Leonard's shirt and pinned the immortal with blue, blue eyes until Leonard realized he couldn't think straight.

He swears and means it when he says, "I won't."