Severus was hardly used to any affection at all, so even friendly, platonic affection from an over-enthusiastic 15 year old girl was disconcerting. He mostly survived it by strictly keeping to formalities, yet she seemed uncannily good at tearing formalities down.
"Very good, Ariana, it is a pleasure to meet you. As you know, I am Severus Snape." He began to feel like a fool. What next, was he to shake her hand? He cursed himself for never becoming sufficiently socially adept. "And it would be a pleasure to come in, thank you. I have indeed brought a housewarming gift. When I knew him, your brother liked mead, but perhaps his tastes had changed over the course of many years..."
Severus began to think about the other guests that would be present. This interaction had taxed him enough, was he to have to go through many more like it? He hoped that he wasn't the only one that brought alcohol, he was going to need it.