Alastor does indeed go to sit in the offered chair, and if his posture is just that bit stiffer than usual, perhaps he manages to mask it well.

"...I need your help."

Much as he is loathe to say those words to anyone, he knows it's best to just get them out there bluntly before he can second guess himself. Rosie, he is fairly sure, won't hold it over him and will understand what asking for help costs him.

"I have, naturally, brought compensation should you agree."