Jacob is absolutely there and ready to party. He came bearing a gift of a leather shoulder holster for Nyx's kukris for when he wants to show them off a bit instead of keeping them in the arminger. He'll end up throwing knives and only be slightly scary about it once he's sloshed on spiced winter mead. (He was loudly complimentary about the mead in-between knife throws, just saying.)
Noct is only a little bit of a drinker. He's used to someone telling him he can't have another glass for some reason or another so he'll have a couple and be a totally flushed lightweight who gives his brother a birthday hug and a fishing lure that he designed himself.
Shiro will stop by for a few drinks and be friendly if a bit standoffish. He always still feels awkward at parties but he likes supporting Outlander businesses and seeing everyone having a good time.