Death the Kid: A little tin of fancy hot chocolate.
Maka Albarn: A white and fluffy scarf, hat and mittens. They will be very warm.
Blake Belladonna: Warm and soft earmuffs and mittens as well! Black, but not so much floofy/puffy as they are soft and fleecy.
Weiss Schnee: A blend of chamomile tea he's put together just for her. The tin will have the ingredients listed on it.
Ruby Rose: Oasis berry tea. (This is a canon tea from the Layton games, and it's a sweet tea. Luke's favorite! He knows Ruby likes sweets.)
Yang: Dream Spice tea (also from the Laytonverse. It's a sweeter tea with a little kick.)
Satsuki Kiryuin: The Layton Elixer. This will be the only gift not delivered in person; he'll write a description of the tea but not sign the card. She'll be able to tell it's from him.
Koishi: A light green fluffy hat and scarf and mittens. They're the same color as her hair. She'll also get a hug.
Zuko: Bitter fruit tea. Another Laytonverse tea, it's a bitter fruity blend and it's specifically called a drink for more refined tastes.
Mamizou: A nice glasses case with a leaf pattern on it.

Anybody else Luke has spoken to more than once will be given a small tin of tea, whatever he thinks they might like!