Just imagine Derek being utterly convinced Santa is real because his mom told him Santa was like mermaids and vampires: Santa existed but was rarely seen within the supernatural realm, and to humans he didn’t exist at all. Because, well, humans. They aren’t even aware of him. Derek can see the logic.
Imagine Derek telling his and Stiles’ kids about Santa - like, proper back story and everything - and Stiles thinking how cute it is, how much he is into it, until he realises, wait -
HE DOESN’T KNOW.
Stiles, of course, goes to Cora and asks, just to be sure (because, hey, you never know) but it turns out Derek was just so into the Santa myth as a kid their parents never had the heart to tell Derek before they died.
I like to think Stiles never tells Derek because Derek Hale got such a shitty deal in life and if Stiles can do this one thing, keep up this one magical thing for him, that’s what he’s going to do (even if it meant having to tackle Erica to the floor that one time and making a complete ass of himself - not that that is unusual) because Derek deserves magic. He deserves a fuck ton of magic.
And that’s the story of how every year Stiles-unsubtle-Stilinski
somehow manages to sneak their kids’ presents under the tree without his husband noticing.
(This usually takes a lot of orgasms - Derek gets very sleepy after orgasms - but Stiles really doesn’t mind the extra effort.)
Last very short Christmas Comic of Pokemon Go before December ends about if the cinnamon roll still believes in Santa Claus. All four of them had the same idea like how a parent treats a child about Santa