[ Sebastian at least takes the vial without hesitation, though naturally, he does study it for a moment. It's not hesitation so much as curiosity, since looking at the ichor inside the vial feels familiar in a way. It's a darkness that just from a glance gives him a similar impression to the tendrils of his own being that are hidden away from mortal eyes, though that's not exactly surprising. With talk of the abyss, of kenoma, there would be a sort of kinship there, even if it's purely coincidental.

He glances up from the vial, first to Howl and then to Ciel. The thoughtful gaze has cooled to one that's more openly appraising of both of them, and it's not something he bothers to hide in the slightest. The quiet calm they've both taken on doesn't unnerve him, but it does interest him. ]

The terms, certainly. They are not common ones, and all together, it is quite distinct. But the underlying ideas... Less so. At a certain point, all belief tends to find the same subjects, if not the same conclusions.

[ To Ciel's point first, and he thumbs over the cork of the vial thoughtfully. He then looks to Howl and nods, though his attention is more intensely on him than Ciel. The drop of mood is noted, and it seems like Sebastian is trying to piece together why as if it were something visible. ]

What happens if I drink it?