It could be that the baby has no traditional mother or father in the sense. It could be a creation of some powerful magic or a sign from a higher power. But if there has to be a human connection, perhaps a human that Castiel saved in the past and some sort of magic transferred a part of their essence to create the baby. This would make for an interesting dynamic as Castiel would have to deal with the human side of the baby's origin.
If there is a mother or father in the fanfiction, it could be another angel. Maybe an angel that Castiel had a past relationship with in the celestial realm. This would add a layer of drama as they might have different ideas about how to raise the baby or what the baby's purpose is.
One possible plot could be that Castiel discovers a baby that has some sort of supernatural origin. Maybe the baby is a key to stopping an impending apocalypse. Castiel then has to protect the baby while also dealing with his angelic duties and the reactions of his friends like Dean and Sam.
In this fanfiction, the mother could be a powerful sorceress. She used her magic to create a baby with Kratos' essence for some grand purpose. But then she disappeared, leaving Kratos to deal with the baby. This would add an interesting layer of mystery to the story as Kratos tries to figure out why she did it and what the baby's true nature and purpose are.
Perhaps it could be a character from an alternate dimension. In some fanfiction scenarios, portals open between different dimensions, and Spiderman could have had an encounter with a female character from another world, which led to the baby.
It could be someone from Stiles' past that he had a brief relationship with. Maybe a girl he met during a summer vacation or a girl from another town that he had a fling with and then lost contact with until she shows up with the baby.
Another option could be an original character created just for the fanfiction. This gives the writer a lot of freedom to create a character with unique traits and a backstory that fits the plot they have in mind for Draco and the baby.
It could be Hinata. Since they got married in the original series, it would be a natural choice for her to be the mother in the fanfiction.
The father could be John Smith. Their relationship in the original story was complex and having a baby together would add a new dimension to their story. It would also explore how they navigate parenthood given their different backgrounds.
Maybe it's a mysterious character. The fanfiction could introduce a new character as the father, someone with a hidden past or special abilities that add an element of intrigue to the story.
It could be a character she has had a long - standing relationship with in the original story. Maybe someone who has been by her side through many adventures and they shared a deep emotional connection which led to the baby.
Perhaps the father is another well - known fairy in Pixie Hollow, like Terence. They could have had a secret relationship that led to the baby. Terence has always been close to Tinkerbell, and their shared experiences with pixie dust and helping Peter Pan could have deepened their connection to the point where they had a baby.