Disclaimer: I don't own Danny Phantom. Butch Hartman does.
It was, all the ghosts agreed, decidedly unnerving to celebrate Christmas when their worst enemy was in attendance with all of them, and actually being nice to them, when yesterday he almost obliterated several of their number.
It was especially creepy when they slowly realized that he gave out the best gifts. They had no choice but to accept them and love them while remembering that it was this creepy, red-eyed, flame-haired, fork-tongued Phantom who had given it to them…yeah, that was hard. That was really, really hard.
They never understood why he held onto the Truce. There weren't any real rules preventing one ghost from attacking another on Christmas, just a vague sense of 'oh yeah, we all agreed to set aside our differences today and celebrate the holidays'.
What the ghosts didn't know, and what Dan himself denied, was that he missed the normalcy of Christmases. No matter how much he mentally raged that 'it isn't true,' he missed the regular arguments of his family. He missed the comfort of being around happy, celebrating people, and he definitely missed all the gifts he had given and received.
In a way, he was trying to make up for not being able to give presents to his true family by giving them to the ghosts. That was why he always put thought and effort into them, and why he made sure they were good or useful presents for the ghosts that received them.
For one day every year, the old Phantom, the carefree ghost half of Danny Fenton, shone through and gazed around at his Christmas.