After Liv and Erik were done admiring each other, and Astrid had momentarily sunk into the background, Erik decided to take the first step.
Literally, in this case.
He closed the distance between the two of them and took Liv into his arms, before planting his lips on hers.
Liv smiled at his initiative, but naturally wouldn't just let him take the lead. She wrapped her arms around his neck and kissed him back aggressively.
Clearly, neither of them were big on shame, as their was no awkwardness in their kiss at all, despite the strange circumstances. They were both physically attracted to the other, liked each other well enough, and since the only possible obstacle, Astrid, was fine with this, there was simply no reason not to enjoy themselves.
Even if they had a spectator.
I shortly considered doing this scene with Erik in his werewolf form, but decided against it, because I wasn't sure how you guys would feel about it.
Let me know if you have any strong feelings about it one way or the other, and maybe I'll do a scene like that in the future!