Celestia is an Oc that belongs to this FNAF Sun X Moon fic, I'm writing! This is her day and night version.
Link: The Day(Cat)acare attendants - Chapter 1 - SushiCat21 - Five Nights at Freddy's [Archive of Our Own] Summary:
Sun and Moon are living the great life. Becoming more than friends, they were content with living the rest of their lives together. Until one of the technicians decide to bunk them in with a cat animatronic. And no, this cat can’t stand up on two legs and talk. This cat is programmed to act just like any other average cat (well almost).
Fluffy scenes and shenanigans ensue. Meanwhile, strange things start happening in the Pizza Plex and it's up to the two of them-and their new fury feline-to get to the bottom of things.
But how far are they exactly willing to go? How far until they get caught up in this mess and there's no turning back?