I'm not sure what her favourite candy is, but I know she loves sweets. It would be wonderful to dress up with her and the others in her mansion. She'd want to have a bit of a party where there'd be wine and song and food, but afterwards, me and her would go alone out into the night to be together for such a special occasion, and come back to her room for an even lovelier time.
I imagine that everyone would dress as they do in the picture, (but with better costumes) but Remi would dress as a valkyrie and I would dress as a lich. Someone who wields a spear called Gungnir is probably into norse mythology.