Philomena is a mentioned only character.
Before the War
Philomena was Princess Celestia's pet phoenix. When she was molting and preparing for renewal, Philomena met Fluttershy, who thought she was sick. Fluttershy's efforts to help proved unnecessary as Philomena soon combusted and rejuvenated herself.
After the War
Philomena's location during the Last Day is unknown. It's possible she was in Canterlot and was killed by the Pink Cloud or that she died and rejuvenated herself as a Balefire Phoenix. Philomena is mentioned by Fluttershy in the Afterword, ten years after Fallout: Equestria, who thinks Pyrelight looks similar to Philomena, hinting that they might be related or even one and the same.
- Philomena was mentioned as Princess Celestia's pet, though not by name until the Afterword.