A plot where Alex and Sara are stranded on a deserted planet together. They have to rely on each other's skills to survive. Sara's combat and survival skills from her time as a pirate, and Alex's scientific knowledge could make for an exciting story of cooperation and friendship. It could also explore a possible romantic relationship between them as they grow closer during their time of isolation.
You can try searching on fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. These platforms have a large collection of fan - created stories, and you might be able to find some great Alex and Sara Lance fanfics there.
Another villain could be a powerful alien race that has invaded Earth X. They are much more advanced than the humans on Earth X and are trying to take over the planet. Alex and Sara would have to find a way to fight them. This could involve Alex using her knowledge of alien technology and Sara's combat skills to find a weakness in the alien invaders.
One possible plot could be that on Earth X, Sara Lance and Alex Danvers are forced to team up against a common enemy. Maybe a powerful dictator has risen on Earth X and they are the only ones with the skills and courage to oppose. Sara's combat skills and time - traveling experiences combined with Alex's scientific knowledge and super strength could make for an interesting dynamic.
One good example could be a story where they get hurt during a fight against a powerful villain. Maybe they are outnumbered and sustain injuries while protecting each other. Another example might be a story set in an alternate universe where they are in a dangerous mission and get hurt due to unforeseen circumstances, like a trap that was set for them.
One common theme is friendship. Since the characters from different worlds (Naruto, and those related to Sara and Lance) come together, their relationships develop and friendship often plays a crucial role in their adventures.
Another common theme is growth. They might start off as rather naive characters but as the story progresses, they learn from their experiences. In some fanfics, they face challenges like dealing with a difficult family member or a natural disaster, and through these, they become more mature and confident in themselves.
Love and romance is also a big theme. Since they have a strong connection in the show, fanfics often delve deeper into their romantic feelings. Some fics might also explore the theme of sacrifice. For example, how one of them would be willing to sacrifice for the other in a dangerous situation. This ties into their heroic natures. There are also fics that focus on their backstories and how those impact their relationship in the present.
A unique OC is key. If the original character has a distinct personality, backstory, and abilities, it can make the fanfic really interesting. For example, an OC with a magical ability in a world of mostly physical fighters like Sara.