One frequent theme is betrayal. Given their somewhat devious natures in their original context, fanfics might explore scenarios where one betrays the other for personal gain. Also, redemption can be a theme, where they try to overcome their past wrongdoings in relation to each other. There is also the theme of competition, as they both strive to be the best in whatever situation the fanfic presents.
I'm not sure which specific Heather and Alejandro you are referring to. But generally, to find good fanfic about them, you can use the search function on fanfic platforms. Try adding keywords like 'romance' or 'adventure' along with 'heather x alejandro' to narrow down the results. You might stumble upon some really creative and engaging stories that way.
A more dramatic title could be 'Alejandro Cruz's Encounter with the OC: A Lethal Weapon Tale of Destiny'. It makes the story seem like their meeting was fated within the world of Lethal Weapon fanfiction.
Well, they could team up to solve a mystery. Maybe there's a crime wave in the city that the official Lethal Weapon characters can't handle alone, so Alejandro Cruz and the OC join forces. They might have different skills and personalities that complement each other, like the OC being really good at hacking and Alejandro Cruz having excellent combat skills.
The theme of found family is also seen in some mal x reader fanfiction. The reader becomes part of Mal's 'family' on the ship. This includes sharing in the joys and sorrows, protecting one another, and having a sense of belonging. It's a way to expand on the community aspect that was already present in the original Firefly series, but now with the reader as an integral part of it.
Friendship is a very common theme. Mal and Evie are often depicted as having a strong, unbreakable bond. Their friendship is shown as something that can withstand any challenges thrown at them.
One common theme is friendship. Fanfictions often show how Mike and Mal build a strong bond. Another theme is growth, as they both develop as characters through their interactions.
One common theme is the exploration of their friendship. Since they come from different backgrounds, it's interesting to see how they bridge those gaps. For example, Mal being from one group and Harry from another.
One common theme is the clash of different worlds. Harry comes from the wizarding world and Mal from the Descendants world, so there's often exploration of how their different cultures and powers interact.
The theme of acceptance is also prevalent. They come from different backgrounds and have different personalities. Fanfictions show how they accept each other's flaws and quirks, which is a key part of their relationship. This can be seen in stories where they have to face judgment from others but still stand by each other.