Sam had known from nearly the moment they met that Steve was his soulmate. That wasn't the problem; the more time he spent with the other man, the more he found himself falling in love with him. He could easily imagine spending the rest of his life with him, watching Steve smile at his stupid jokes, running with him in the morning, curling up in bed with him at night.

But Sam wasn't completely human; under the light of the full moon, he turned into a sleek panther. And while they hadn't been together on a full moon yet, Sam knew it was only a matter of time, that he couldn't keep his identity hidden from Steve forever. And he didn't want to - Steve deserved to know all his secrets. While Steve was nearly a hundred years old, Sam could expect to live twice that long, and possibly longer. That was the crux of the problem; sure, Steve hadn't shown any signs of aging yet, but that didn't mean he'd still look like he was thirty in another century. Sam could bite him and change him, but not without his permission - and that required him to explain what he was first.

It was a few nights before the full moon, and they were in Europe, following Bucky's trail through Switzerland. Steve was flipping through the file folder, and Sam was about to settle into bed with a battered paperback, as usual. But instead, he sat next to Steve on the bed. "Hey, can we talk?" he asked quietly.