Well, perhaps a plotline could involve the Arrow teaching some of the Avengers his unique combat techniques. For example, showing Hawkeye some new archery tricks. And in return, the Avengers introduce him to their advanced technology for upgrading his arrows.
A possible plotline is that the Arrow gets involved in an Avengers - level threat that his city couldn't handle alone. He has to adapt to the Avengers' way of working, which is on a much larger scale. There could be conflicts at first as he tries to fit in, but eventually, they all work together to save the world.
The Arrow is sure to be a main character. In addition, Hawkeye would be a crucial character in this fanfiction. Since they both are archers, there could be a lot of interaction between them, like competing or collaborating in archery - related tasks. And of course, Captain America with his leadership skills would also be among the main characters to lead the team that now includes the Arrow.
A great plotline in Arrow fanfiction could be the introduction of a new group of anti - heroes. They initially clash with Oliver and his team but then end up joining forces to take on a bigger threat. This could lead to some really interesting character development and power dynamics. There could also be a story where Oliver loses his memory and has to rediscover who he is while still being hunted by his enemies. Or a plot where Felicity creates a new technology that gives the team an edge in combat, but it also comes with some unforeseen risks.
One interesting plotline could be the Flash and Arrow teaming up to face a common enemy that has powers beyond their usual foes. For example, a meta - human with the ability to manipulate time, which forces them to use their combined skills of speed and archery in creative ways.
Another plotline might involve the character's struggle to recover from the knee injury. It could show their determination to not let the injury stop them from their quest or daily life, with them having to adapt to their new physical limitations.
In such fanfiction, a common plotline is that Harry's decision to join Voldemort creates a power shift. He might use his status as the 'Boy Who Lived' to undermine Dumbledore's reputation further. Since many in the wizarding world had put their faith in Harry, his joining Voldemort could lead to widespread panic and confusion. Harry could also start to recruit other disillusioned wizards to Voldemort's cause, using his own charm and the false narrative that Voldemort is actually a liberator of the wizarding world from the old, restrictive ways.
One possible plotline could be Naruto being transported to the Arrow universe and attracting the attention of various female characters. Maybe he uses his ninja skills to help them in their battles against villains in Star City, and in the process, romantic interests start to develop.
One possible plotline could be that Felicity discovers she's pregnant just as a major new threat emerges in Star City. This creates a dilemma for her as she wants to help the team but also protect her unborn child.
Another plotline could involve Percy making new friends in the navy. These friendships could be tested during dangerous missions or when faced with internal conflicts within the naval unit.
One interesting Avenger - Hydra fanfiction could be about a scenario where a Hydra agent has a change of heart and secretly helps the Avengers. This could add a lot of intrigue as the Avengers are initially suspicious but gradually come to trust this former enemy.
One interesting Avenger lice fanfiction could be about how the Avengers deal with a lice outbreak in the compound. Maybe they use their super - powers in unexpected ways to get rid of the lice. For example, Thor could use his lightning to zap the lice away.