One possible plot could be that the vampires from Twilight somehow end up in the world of Friday the 13th. Maybe they get transported there by a strange magical event. The vampires' powers would be a new and terrifying element in the already spooky Friday the 13th setting. They could either be enemies of Jason or form some sort of uneasy alliance with him.
One idea could be a crossover with 'Nightmare on Elm Street'. Freddy Krueger could invade the 'Friday the 13th' world and start terrorizing the campers. Jason Voorhees would then have to face this new threat. It could be an epic battle of two horror icons.
Jacob, in his werewolf form, would be more likely to directly confront Jason. He's used to fighting against threats, and his strength and speed as a werewolf would make him a formidable opponent. However, he might be a bit overconfident at first, not fully realizing the unique danger that Jason represents.
First, decide which two or more universes you want to cross over. For example, if it's 'Friday the 13th' and 'Alien', think about how the two different types of horror can blend. Then, introduce the setting. If it's at Camp Crystal Lake, describe the spooky atmosphere. Next, bring in the characters. Start with a character from one of the universes, like Ripley from 'Alien' arriving at the lake. Then, build the conflict. Maybe there are strange alien - like creatures emerging from the lake, and Ripley has to team up with Jason (in a strange way) to face this new threat.
One idea could be a crossover with 'Nightmare on Elm Street'. Jason Voorhees could find himself in Freddy Krueger's dream world. Maybe the two iconic killers start to compete for victims, which would create a really tense and spooky situation.
Ruby's speed might increase even more due to the sense of danger from the Friday the 13th elements. She could be constantly on high alert and her scythe attacks could be more erratic and fast - paced.
There's also 'Jason and the Newcomer'. In this fanfiction, a new character arrives at Camp Crystal Lake with a mysterious past. This character seems to have an uncanny ability to sense Jason's presence. The story delves into their strange connection and how it affects the events at the camp.
In a crossover with another horror franchise, like 'Scream', the killer from 'Scream' could be revealed as the mastermind behind Jason's actions. So instead of Jason just being a mindless killer, he's being manipulated by someone else for their own twisted reasons. This would completely change the dynamic of the fanfic.
Naruto's Rasengan would be a very effective weapon in the Friday the 13th universe. He could use it to blast away any threats, like the masked killers or other dangerous creatures. His ability to create shadow clones would also be useful for scouting the area, as the Friday the 13th settings are often full of hidden dangers. He could send clones in different directions to look for exits or other survivors.
The love triangle in Friday the 13th fanfiction can be really engaging. It might be that one character is in love with a potential victim and the killer in some strange way. Maybe the killer has a hidden side that draws the character in, while the victim represents safety and normalcy. This can lead to some really tense situations as the character has to decide who to side with, all while the threat of Jason Voorhees looms.