He doesn’t know what to do. He doesn’t know what to do and it’s killing him, because here he is, trapped in the past and unable to get back but having made so much progress and so many good, actual relationships here, that he doesn’t think he would willingly /want/ to go back. He misses it, of course; being a Necromonger, being a soldier, but that absence of bloodlust hadn’t killed him yet and frankly, he was starting to think that maybe it was better to be a healer than a killer. Of course, when he’d first gone through that damned wormhole - a fluke of the navigations that had changed pretty much /everything/ - he’d left behind everything, too. Everything he’d known and cared about, gone in the blink of an eye, and he’d spent days trying to get back, but of course, wormholes don’t go both ways. He’d been transported years from his own timeline - the Necromongers didn’t even /exist/ here and now - and he hadn’t known what to do. And with no need of a military in this near-utopian era, he’d had to find another way to make a living, another way to get over the loss of his bonded in such a monumental way.
Enter medical school, and Starfleet, and Jim fucking Kirk. It was interesting learning about alien cultures and biology when before he’d only been interested in destroying human settlements, and it ate up some time and distracted him from the loneliness, but he needed to get into space again, to find out if he really was stuck here for good, so becoming a doctor for Starfleet helped ease it along. Jim just came along with it, as bright as the sun and the complete opposite of Riddick. He couldn’t really compare them, though; no, they were both gorgeous, both dangerous in their own rights, and both their smiles lit up the room, but where Jim was brave and daring and willing to sacrifice himself for the ‘good of mankind’, Riddick couldn’t’ve cared less. Where Jim tried to keep violence as a last resort, it was the first scenario Riddick brought up. Where Jim certainly had a juvie record and had served a day or two in jail, Riddick had done hard time in and had escaped from at least ten prisons throughout various galaxies. Where Jim was here, Riddick was not. Riddick was gone, for /good/, on the other side of a wormhole he couldn’t go back through, and Siberius - /Leonard/ - needed to realize that.
He doesn’t think he ever did.
Fast forward, two years into the five-year mission, four-ish years into his relationship with Jim, who was as understanding as he could be about Leonard not wanting to say much about his past (“My old - partner… I haven’t seen him, in a while.” And Jim knew that tone, and he didn’t press him for answers) (“Did you do anything before you were a doctor?” “I was in the military, on a settlement far from Earth.” And Jim would want to ask, but his own demons would keep him from it, and they’d move on to another topic).
And then the fucking skiff with his Furyan - /his Furyan/ on it, sputtering into the Enterprise’s space just enough to pick up the weak distress signal, and the next thing he knew his long-lost mate was being wheeled into Sickbay with a fractured femur and a punctured lung, but dammit if he wasn’t gonna get out of this alive.
And Dr. McCoy used the surgery to distract himself some more, working on autopilot to keep the damn man breathing, because if this was real, if /he/ was real…
And he was. Leonard - Siberius - god, he didn’t even know anymore - he could touch him, could smell him, he was right there, sleeping off the worst of it under a thin white sheet while Siberius was trying not to have a panic attack because Riddick was /here/, he was here and he was safe now, he was safe with him, he was /with/ him, /god/ it had been /so long/…
And he - he could do nothing but sit and wait. Sit beside the bed, keep himself from holding his mate’s hand just to feel the warmth, feel his pulse, and wait. And Jim… oh, Jim. The captain had already come in to see their newest strange addition, rightly wondering if the man was dangerous to the crew, and Leonard had told him no. He didn’t know, of course; he trusted Riddick, he trusted him with /everything/, but he’d left him so long ago, who knows what could have happened in those years since he’d been gone? If he’d been usurped? And god knows what made him show up /here/, in a Necromonger skiff beat to hell and back, in a universe that wasn’t his a few hundred years in the past. He could very well not be the same man he left, and he could very well be dangerous, especially given the strange new situation he was in (Riddick, he had always hated hospitals, and the Enterprise was too bright and too /good/ for his Furyan to bear. He’d need to get him something for his eyes before he woke up). But he had to trust his instincts, and he was hoping they were right.
Jim had trusted him in response. Jim had also seen the way he’d reacted to Riddick’s presence; his tense shoulders, hunched back, pale face and shaking hands (god, they never shook…), and inferred his own theory about the man in his Sickbay. He’d placed a hand on his shoulder, squeezed it tight, then bent down and kissed his temple before making his leave.
Leonard stopped him before he left, not taking his eyes off of Riddick, his Riddick, watching his chest rise and fall under that flimsy white sheet. “Jim?” He didn’t need to turn to know he’d stopped. He’d thought his senses had grown weak over the years, but they’d picked right back up again, almost too loud, too overbearing now. He’d heard Jim stop. “Give him a chance first, okay?” He’d never admit his voice choked up on the last word, and neither would Jim, but he heard him say “okay, Bones” and then he was gone, and Leonard - Siberius - he was sighing like the weight of the Basilica was lifted from him, and all he could do was wait.
Because he didn’t know who he would choose, if push came to shove. He didn’t know, and he didn’t want to have to. And Jim had just gave him the go-ahead, that he could try and make all three of them work. Now all that was left to do was see if he could get Riddick on board.