Third person pov.
After a long debate over if they should celebrate their birthday on different days of the year, or just keeping it the same, they went with the simpler. All of them got their own job for the day and how it would represent all of them.
Red job was obvious to anyone who ever talked to him. He baked the cake. The icing was always white, and always had five, 1 to 1 and a half cm, layers. Angel, chocolate, lemon, a fruity mix and red velvet. He always choose a different filling each year; the first being just icing, but it quickly ended up being a competition against himself.
Green was in charge of what they did; deciding if it would be a large event or just between a few family and friends. He had to make the list a month in advance and would place suggestions on what the others liked. His job also included where, and when was the latest people could be there.
Blue and Shadow would always make some form of furniture together for the house. It was always simple as they didn't have a lot of skill in that department by any means. But the heroes would never get rid of them, it just had too much sentimental value to it.
Vio had long since given himself the job of budgeting. In no way grand but someone had to do it. He also made sure none of the others ever peaked at their presents, Shadow was definitely an obstacle on that front. He made sure the other had the supplies they needed. And at some point he ended up with the job of making the invitations.
Of course some traditions developed between their Father and the Princess. She had gotten them each a charm bracelet and every year they'd get a new piece. The first a little marble of their colours, the second a silver copy of their second weapon, the third represented a hobby of theirs, and the fourth their element. The Father would get them either armor or a weapon each. Shadow's first gift from him even became his second weapon, a whip, with an obsidian gem at the base.
Each year was something special between them, as it reminded them of who they had.