Oh, yes, Severus was 'in'. It was not quite as good as the dungeons of Hogwarts with unknown tons of stone protecting him from the outside world, but losing himself in the brewing of potions had ever been his one and only solace from whatever inward pain presently ailed him.
"In the back," he called, the voice approaching unfamiliar to him. He was in a delicate spot in his blood-replenishing potion, so couldn't leave the stirring process to come forward. Thirteen widdershins, and done. He tapped the stirring rod on the side of the cauldron, wiped it on a towel before setting it aside and glanced up.
Lupin. He glanced at his cauldron. He had no idea how much lycanthropy affected the senses of the man, but ever since he'd learned of Lupin-the-senior's condition, he'd surmised that the noxious potions fumes were one of the reasons he'd always been such pants at potions. That, and an inability to handle a wide variety of silver cauldrons, stirring rods, mortar and pestle and so on.
He hadn't seen this Lupin since the battle with Bellatrix, in which he'd acquitted himself well in Severus's opinion. The killing curse was not an easy thing to cast, and Severus had been impressed that Teddy Lupin had accomplished it.
Certain he was that the other Lupin never would have done.
"Mr Lupin. If you give me a moment, I'll come to the front. Whatever business you have on hand, I suspect you'll be more comfortable there." Then again, the new moon was tomorrow. If the werewolf senses waxed and waned like the moon that dictated the change, perhaps Lupin wasn't bothered by such things today.