I don't think we can assume she's a villain. Just because she has 'another story' doesn't mean it's a story of villainy. She could be a bystander who gets involved in the events in Gotham in a positive way, like helping Batman or the police in some way.
Ingrid faced a series of challenges and unexpected events. But it's hard to give a detailed account without knowing more specific details of your question.
Their relationship would likely become more protective. Gregorio would be constantly worried about Ingrid and the baby. He might start taking on more dangerous tasks himself to keep her out of harm's way. Ingrid, on the other hand, might feel a bit smothered at times but also appreciate his concern. They would also have to communicate more about their future plans, both as spies and as parents.
I don't know who created the 'Ingrid Never Ending Story'. There could be an individual writer, perhaps an amateur or a professional, who came up with this concept.
I'm not sure specifically what 'Ingrid Never Ending Story' is about as it could be a very unique or personal creation. It might be a story that features a character named Ingrid and has an ongoing, perhaps fantastical or complex plot that seems to have no end.
One common theme is the clash of different cultures. Since Ingrid is from a different background, her encounter with the Naruto world's unique culture often leads to interesting situations and misunderstandings at first, which then develop into mutual understanding.
A more romantic take on a Young Dracula Ingrid and Will fanfiction could be that they fall in love despite the differences between vampires and humans. Their love story would be filled with obstacles. They might have to hide their relationship from Ingrid's vampire family who might not approve, and also deal with the fact that Will's human life is so different from Ingrid's vampire existence. But in the end, their love could bridge the gap between the two worlds.
It's purely fictional. The plot and characters of Ingrid Goes West are the imagination of the filmmakers and writers, not based on real events or people.