//This felt weird to writ since I love Christmas...

He never understood it. Sure, he'd hear people talk and sing about it all the time...but none of it made sense to him. Maybe it was because he never payed attention to this time of year as a kid, so he didn't ask why there'd be a man leaving presents. He didn't understand the concept even more as an adult; people (in his life, at least) don't do nice things without expecting something in return. People don't give gifts so carelessly and without question. People didn't gather at the dinner table to be merry. So he ignored the mind numbing tunes and the wishes people gave him for a happy holiday. He didn't even try to have whatever Christmas was in his life, already knowing the answer would fall under "it's silly, a waste of precious time".
As an adult, his knowledge was still limited and his care for it slowly dwindling into nothingness as painful memories were drained from the back of his mind.

Of course, that all had to change upon becoming a father. Especially since the kids he adopted knew what Christmas was. He improvised, letting them lead the way with how to prepare and what to prepare with. A tree, bright lights, shiny balls, cookies, presents, a big dinner...all the things he didn't experience. But he'd push the pain aside to focus on giving his kids a happy childhood. It wouldn't be normal, but the least he could do was be the cause of happy memories.
It took awhile for him to listen to the songs. The songs just...irrated him, for some reason. The happy tunes made Sebastian grumpy, but he pushed through with them. For his family.

But nobody knew the silent resentment behind his eyes, no one knew the bitter sadness boiling inside with a cup of eggnog. Not even his brother, who also grew up without Christmas, knew what pains the confusing season brought on. But he never showed these feelings, giving a smile and a laugh at the songs and sickenly sweet movies.
At least the only thing he did care and love about the time was almost always there.
The smiles of his family. The hugs and warm greetings at that big dinner. The overwhelming amount of love swirling in the household. That's what made it all worth it...