One possible scenario in this fanfiction could be that Finn's transformation into a vampire brings out a whole new side of his personality. He might struggle with his newfound thirst for blood while still trying to uphold his heroic values. Maybe he teams up with Marceline, who is already a vampire, and she teaches him how to control his urges.
Yes, there are quite a few. You can find some on fanfiction websites like Archive of Our Own. Just search for 'Adventure Time Finn and Marceline love' and you'll get a bunch of stories, some exploring their relationship in different ways, like how they might have fallen in love during their adventures.
There could be a fanfic where Finn's death is a sacrifice to save Ooo from a great evil. In this story, his death might not be in vain as it inspires others to be braver. Maybe Marceline, who has seen a lot of loss in her long life, becomes a mentor to the younger characters as they cope with Finn's death, teaching them about the importance of memory and how to keep Finn's spirit alive.
One interesting theme is Finn's search for identity. Since he's a human in a strange land full of magical beings, he often questions who he is and where he belongs. Another theme could be his relationships, like his brotherly bond with Jake or his complex feelings towards Princess Bubblegum.
Sure. There are fanfictions that revolve around Finn's heroic deeds. He's a very popular character, and many writers create stories that stay true to the family - friendly nature of the show. They might write about Finn's attempts to protect the Candy Kingdom or his quests to find magical items, all without any inappropriate content.
It can be quite divisive. Some fans who are very attached to Finn may be really sad or even angry about the idea of him dying in fanfics. They might see it as a negative take on the character they love. However, others may appreciate the exploration of deeper emotions and different storylines that such a concept brings. It allows for more complex character development for the remaining characters as they deal with grief.
Obviously, Finn and the Jungle Princess are the main characters. Finn, a brave and adventurous boy, and the Jungle Princess, who has her own set of skills and knowledge about the jungle environment.
Well, perhaps Finn gets bitten by a vampire while on one of his adventures in the Land of Ooo. As a vampire, he has to adapt to a new lifestyle. He might start to prefer the night and avoid the sun. His diet could completely change, which would be a big shock to his friends who are used to his normal eating habits.
The main characters are Finn, a brave and adventurous human boy, and the Water Princess. Finn is known for his heroics and his sword - fighting skills. The Water Princess has control over water and is from the Water Kingdom.
A really cool fanfiction could be set in an alternate universe where Finn was born a vampire. He has to grow up in a world that fears him, but he still has the heart of a hero. He might use his vampire abilities for good, like super speed and strength, to protect those who are weaker, and in the process, he tries to change the perception of vampires in Ooo.