Jack and May are the protagonists. In fanfiction, they could be given different personalities and backstories from the original source (if there is one). They might be best friends, siblings, or lovers, depending on how the author of the fanfiction chooses to portray them.
A powerful sorcerer could be the main antagonist. He might be jealous of Jack and May's emerging powers and see them as a threat to his own plans of ruling the land. So, he tries to stop them at every turn, creating various obstacles and sending his minions after them.
Another idea is that Jack and May are given a special task by an ancient being. They have to find a set of magical artifacts scattered across their land. However, there are other forces that also want these artifacts for evil purposes. Jack and May's journey is filled with challenges, and they also have to deal with their own personal growth and relationship development as they complete the task.
Another fanfiction idea could be a time - travel aspect. Maybe Jack and May get sent back in time to when their world was first created. They then have to figure out how to get back to their own time while also dealing with the primitive and often dangerous conditions of the past.
I'm not entirely sure as it's not a very common or well - known specific 'fanfiction'. It could potentially be a play on 'Once upon a time' but for a series in the form of fan - created fiction. Maybe it's about a unique take on a beloved series, with its own set of characters and plotlines that are inspired by the original series.
The main protagonist is often a great character to focus on. Their journey, growth, and the challenges they face can be really interesting to explore in fanfiction. For example, if they start as a naive character and gradually become a hero, it can make for a great story arc.
One idea could be a crossover where characters from 'half upon a time' meet characters from another well - known fairy - tale world. This could lead to some really unique and humorous interactions as they try to navigate each other's rules and cultures.
I'm afraid I don't have any particular 'half upon a time series fanfiction' to recommend. However, when looking for good ones, check the reviews and ratings on fanfiction platforms. Look for ones that have a high number of positive reviews. Also, if there are forums or groups dedicated to the series in question, ask there for recommendations. They might be able to point you to some great 'half upon a time series fanfiction' that you wouldn't find on your own.
One popular theme is Jack Frost's origin story. Many fanfictions explore how he became the Jack Frost we know, his past life before being a magical being. Another theme is his relationships, like his friendship or possible romantic relationships with other characters from Once upon a time.
You can start by looking on fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. AO3 has a large and diverse collection of fanfictions, and you can easily search for Jack Frost fanfictions using the search bar. FanFiction.net also has a lot of works, but the quality may vary more. Another option is to check out Tumblr. There are often fanfic writers who share their works or recommend others' on there.