Rolling his eyes as Sirius managed to squeeze a harsh bark at the house-elf in between lines of the cheery Christmas song without missing a beat or even sounding the least bit off, Remus pulled out the candelabra and considered them for a moment before grabbing the nearby wreath, looping it around his arm, and going towards the front door.
So maybe he wasn't the most holiday-spirited of the bunch, this was true. And perhaps he still wasn't sleeping well and still found plenty of time to brood when no one was looking. Sirius had enough spirit and energy for all of them and then some, and Remus, having sorely missed that aspect of Sirius's personality, wasn't about to complain. At least until Sirius tried to stick fake antlers on his head.
"May your days be merry and bright," he sang quietly as he went to work, trying his best to make the decorations look perfect. "And may all your Christmases be white."