Lestat's smile spread wider for that under the next kiss, pleased in a way he hadn't expected to be. He wouldn't have been too surprised if Louis wanted none of the song at all, given the givens.

"Well, if you do not hold the poor acoustics against me—"

And that he is laying on his side, terrible for breathing, but he's very talented and a vampire and hardly needs to project, so he can make do.

So he sings. It's a gentle, quiet song anyway, fragile in delivery, in lyric, and it's easy enough to scale it down into a tender little lullaby between them. Unselfconscious, finding Louis' hand to twine his fingers through his as he serenades him.