In most cases, Richard would be the obvious choice as the father. Their relationship is central in the story, and it would make sense in the context of the fanfiction for him to be the father.
There could also be a situation where Kahlan was impregnated by a magical entity in a strange and unexpected turn of events. This would force her to deal with not only the pregnancy but also the mystery of the father and what it all means for her future.
One possible storyline could be that Kahlan's pregnancy is a sign of hope in a time of great despair. Her unborn child could be seen as a symbol of a new beginning for the world she lives in. Maybe she has to go into hiding to protect the baby from the forces that want to use its power.
Zeddicus Zu'l Zorander is a beloved character in fanfiction. His wisdom as a wizard, his humorous side, and his role as Richard's grandfather - like figure are often the focus. Fanfictions might show his teaching moments with Richard or his own solo adventures dealing with ancient and dangerous magic.
It could also be someone new, a character created specifically for the fanfiction. Maybe a powerful new demigod who catches Annabeth's eye, and their relationship leads to the pregnancy.
It could be a long - lost love from Mavis's past. Maybe someone she thought she'd never see again but who re - enters her life right before she discovers she's pregnant.
It could be another powerful magical being in her realm. Maybe a long - time ally or a mysterious figure that has been in the background of the story's world. This would add an element of mystery and intrigue to the fanfiction.
In some fanfictions, the father could be a human character. This would add an interesting dynamic as it would involve dealing with the differences between a human and a Digimon in a relationship and during pregnancy. It could also lead to a story about acceptance and dealing with the unconventional nature of such a union.
It could be one of her close friends or classmates in 90210. Maybe someone she had a brief fling with during a party or a school event.
Maybe it's a new character introduced just for this plot twist. This would add an element of mystery and new drama to the story.
It could be Ron. Since they have a relationship in the original story, it's a very likely option. Their relationship could be further developed as they face the new chapter of becoming parents together.
Perhaps it's a human boy who accidentally wandered into the fairy world. Tinkerbell, being curious, interacted with him, and in a magical turn of events, she became pregnant. This would create a lot of drama as the fairy world and the human world don't usually mix in such an intimate way, and there would be a struggle to figure out how to handle this situation.