There's also the possibility that it's an unknown stallion from a far - off land. Twilight could have had an adventure in a different region and met someone there. This would add an element of mystery to the fanfic, as the readers would be curious to learn more about the father's background and how he and Twilight met.
One possible plot could be Twilight Sparkle facing challenges during her pregnancy. Maybe she has to deal with magical imbalances in Equestria that are affecting her unborn foal. Another idea is that her friends come together to support her through the process, and they learn about new types of magic related to birth and new life. It could also involve Twilight preparing for the future of her foal, like choosing a proper education in magic for it.
One possible storyline could be that Twilight Sparkle gives birth to a magical foal with unique powers. Maybe the foal inherits Twilight's love for knowledge and has an instant connection to the magic of Equestria. The story could then focus on Twilight raising the foal and teaching it about friendship and magic.
It could be a mortal man who somehow managed to catch Artemis's eye. Maybe he was a great hunter like her, and their brief encounter led to the pregnancy.
It could be a mysterious and powerful wizard. He might have used his magic to be with Ciel in a way that led to the pregnancy. His powers and knowledge could play an important role in the story, perhaps he has to use his magic to protect Ciel during the pregnancy.
The most obvious choice would be Percy Jackson. Given their long - standing relationship in the original series, it makes sense that he would be the father. Their relationship has been through so much, and having a child together would be a new chapter in their story.
There could also be a new character introduced as the father. Maybe a powerful Force - sensitive being from a previously unexplored part of the galaxy. This would add an element of mystery to the fanfic. The new character could bring new powers or knowledge that Rey and her child could inherit or learn from.
Maybe Simon. If the fanfic takes an alternate path where Clary and Simon end up in a romantic relationship, he could be the father. However, he might be away or unable to be with her when she gives birth.
One possible plot could be centered around the challenges Twilight Sparkle faces during her pregnancy. Maybe she has to deal with her own insecurities while still having to manage her duties in Ponyville. For example, she might worry about how her friends will view her as a mother and if she can still be a good leader. There could also be a magical element involved, like her unborn foal having some special magical abilities that are causing complications during the pregnancy. Another aspect could be the support she gets from her friends, like Pinkie Pie trying to cheer her up when she's feeling down, and Rainbow Dash protecting her from any potential threats.
In the fanfiction, Twilight Sparkle giving birth could bring about a more unified Equestria. The foal could be a symbol that brings all the different pony tribes closer together. Also, the new life might inspire new laws or ways of living in Equestria. Maybe there will be more focus on education and nurturing the young with Twilight as a role model for motherhood. It could also lead to new magical discoveries as the foal grows and shows its unique powers.
It could be some other wizard who Harry had an unexpected encounter with. Maybe it was a wizard who was secretly in love with Harry and used some sort of love - related magic that had an unforeseen consequence.