It could be Michael. Since they have a complex relationship in the Roswell series, it's possible that their relationship takes a new turn and he is the father. Maybe they had a passionate night together that led to the pregnancy.
There's also a chance that it could be a new character introduced in the fanfiction. This new character could be from out of town, or maybe even an alien in disguise who sweeps Maria off her feet and is the father of her unborn child.
Perhaps it's Max. He has always been there for Maria in some ways, and an unexpected moment of closeness between them could result in him being the father. He is also a central character in the Roswell story, so this would add a whole new layer of drama to the fanfiction.
One possible plot twist could be that the father of Maria's baby is not who she initially thought. Maybe there was some sort of mix - up at a fertility clinic or she was deceived by someone she trusted. Another twist could be that Maria discovers she has some sort of alien - related pregnancy, given the Roswell theme, which could bring in all sorts of strange powers or abilities for the unborn child. A third twist might be that Maria decides to keep the pregnancy a secret from most of the people in Roswell, but as she tries to hide it, she gets into all sorts of comical and tense situations.
In some fanfictions, it could be Gray. Their rivalry - turned - friendship has a lot of potential for such an unexpected plot twist where Gray is the father.
There's a chance it could be a new character introduced in the fanfiction. Maybe someone who has a mysterious past and enters Annabeth's life briefly but leaves a big impact, resulting in her pregnancy.
In some fanfiction scenarios, the father could be a character who was under a spell or some sort of mind - control when the encounter with Kiba happened. This would add an interesting twist to the story as Kiba has to deal with not only the pregnancy but also the mystery behind the father's identity and the circumstances of their encounter.
It could be one of her close friends from the guild. Maybe Jellal, considering their complex relationship in the original story. There's already a lot of history between them, and this could be a new development in their relationship.
It could be a long - time boyfriend that we haven't known much about in the original story. Maybe he's a character who was in the background but now becomes central to the plot.
It could be her existing partner from the original story. For example, if it's a story where she's in a relationship with Edward, then he would be the likely father.
There's also a chance that it could be a god in disguise. Gods have been known to have relationships with mortals and demigods. So perhaps a god took on a human form and had a relationship with Thalia, resulting in the pregnancy.
For Michael's family, if they have been in hiding or trying to keep a low profile in Roswell, the pregnancy could be a big threat to their secrecy. They might be hesitant to get involved for fear of attracting unwanted attention. Maria's family, being human, might have a hard time adjusting to the idea of having an alien - related pregnancy in the family. They could initially be resistant, but over time, with understanding and seeing Michael and Maria's commitment, they might come around.
It could be his long - time partner. They might have had a very loving relationship that led to this situation.