Plum's been a very good girl for far too long. The special treat she wants this year is Santa.
Santa's been a little disenchanted with his job lately. Mrs. Claus ran off with Rudolph, who kept putting his nose where it didn't belong -- all Santa's reindeer are shifters. What? You didn't think he'd keep a herd of fat lazy deer around all year, eating their heads off, when he only needed them one night a year?
Anyway, the Mrs. ran off with Santa's ex-best friend, so he's been alone for a while now. So you can see why the idea of a special treat got his juices running. He thinks Plum's giving him a treat, but he read the note wrong. Plum's been a very good girl, and he's supposed to give her a special treat. But that's OK, because the treat Plum wants is Santa.