Another possibility is that a character from Glee, say Rachel Berry, discovers she has some sort of meta - human ability similar to the Flash. The Flash has to come and train her to control it while also dealing with the chaos that her new powers cause within the glee club dynamic.
Well, it could be a story where they team up to fight a common enemy. Maybe a villain who has the ability to manipulate time or something. Spiderman could use his intelligence to come up with a plan, and The Flash could quickly execute it with his speed. They would learn from each other's strengths and weaknesses along the way. For example, Spiderman could teach The Flash about using the environment to his advantage, while The Flash could show Spiderman how to move even faster in a fight.
Another theme is the combination of their powers. Many stories explore how the Arrow's combat skills and the Flash's super - speed can be used together to defeat enemies. It's like seeing two different forms of heroism merge into one strong force. This could involve them creating new strategies or tactics that are unique to their combined abilities.
One common theme is a race or a competition between the two speedsters. Since both Flash and Quicksilver are known for their super - speed, it's exciting to see them compete in a friendly or not - so - friendly race. Another theme could be them teaming up against a common enemy. They might combine their speed powers to take on a powerful villain.
There could also be other characters involved. For instance, some of the Flash's friends or allies from his usual superhero team might make an appearance. They could either be helping the Flash deal with Jinx or getting caught in the crossfire of their encounters. Additionally, Jinx might have her own group of followers or partners in crime that could add more depth to the story.
In a 'Supergirl meets the Flash fanfiction', they might team up to fight a powerful common enemy. For example, a super - villain who can manipulate time and space, and only their combined powers can stop him.
Fanfiction.net is another option. It has a large collection of fan - created works. However, the tagging system might not be as precise as AO3. But with a bit of digging and using the search bar for 'Flash meets Quicksilver', you may find some interesting fanfictions.
In a 'Team Flash meets Supergirl' fanfiction, there could be an epic team - up. The Flash might use his super speed to save Supergirl from a kryptonite - powered trap. Then they could join forces to fight a common enemy like Lex Luthor or an alien invasion. The scientific minds in Team Flash could also help Supergirl understand some new aspects of her powers.
One interesting plotline could be Jinx causing chaos in the Flash's city, and the Flash having to figure out how to stop her without using too much force. Maybe Jinx has stolen some important tech that could disrupt the city's power grid.
Lex Luthor could be a great main antagonist. He could be jealous of their combined power and see them as a threat to his plans of world domination. He might create some high - tech weapons specifically designed to counter their abilities.