Lyrium doses are an every-few-days sort of thing, so Barrow has had a bit of lead-up to the time that he stops taking it. That day will be tomorrow, and experience has proven that it won't be awful, not immediately, but he's still considering it an official Day One. That means being in the infirmary, under observation, which is a hell of its own kind, as far as he's concerned.

So the night before, he takes himself out to the Loose Noose and proceeds to enjoy a generous portion of whiskey (of which, much like lyrium, he requires an enormous amount to even feel it). He's there alone, serenely playing solitaire by the fire, enjoying his last night of calm before the storm.