Eyes fluttered shut, Nathan didn't move. He didn't move because he wasn't certain what would happen if he did. He wanted to get up, to gently displace Enfys and leave the room, leave her behind, go find Jim and bury himself in him. Because Jim was now, was fresh and clean, was not Merlin. Because Jim loved him, mistakes and all, failures and all.
It was equally as likely - more than equally likely - that Nathan would rock forward, though. That he'd twist his fingers into fiery red hair, that he'd crush his mouth to Enfys' in a hunger that was threatening to burn him alive. He might not leave if he moved. He might do everything but leave. So he remained motionless, trying to get up the strength to leave Merlin behind.
"Not fair, Enfys," he protested hoarsely, voice still rough with desire, though Nathan wished it wasn't so. "Never once have I chosen anything over you and you know it. Now you want what I have yearned for all this time? Now you wish to begin what you cannot finish?" His head instinctively turned, seeking her skin with his lips, because he couldn't not, even as he wanted to pull away. His mouth pressed to her pulse point and Nathan tried, once last time, to end this. "It is unkind to toy with me, Emrys. I did not think even you were that cruel."