Since there aren't a ton of these types of fanfictions, but if there were, a common theme might be the exploration of their forbidden or unexpected attraction. Given their complex relationship in the original comics, it could be about how they overcome their initial animosity to develop feelings for each other.
One great 'Jason Todd and Damian Wayne' fanfiction is 'Brothers in Arms' which explores their complex relationship in a really interesting way. It doesn't have any lemon elements though. Another one could be 'The Dynamic Duo Redux' where their characters are well - developed and the story focuses on their adventures together. There are not many lemon fanfictions about them that are widely known, as their relationship is often depicted in a more platonic or brotherly context in most mainstream works.
One common theme is redemption. Jason has his troubled past as the Red Hood, and in many fanfictions, Damian helps him find a path towards redemption. For example, in some stories, they work together on a mission that makes Jason see the value of his place in the Bat - family again.
One possible scenario in this fanfiction could be that Jason Todd and Damian Wayne initially have a tense encounter due to their different upbringings and personalities. Jason, with his more rough - edged past, might be skeptical of Damian, who was trained in the League of Assassins. Talia could act as a mediator or perhaps have her own motives for bringing them together. Maybe she sees potential in their combined skills for some greater purpose she has in mind.
Jason and Damian could have a battle of wits at first. Since Jason has his own sense of justice which has been shaped by his traumatic experiences, and Damian has the strict discipline of the League of Assassins. Talia might be torn between the two, as she cares for Damian as her son and has a certain relationship with Jason as well. Maybe she tries to make them see each other's points of view.
Jason Todd, who was brought back from the dead and has a bit of a grudge against the Bat - family at times. And Damian Wayne, who is trying to prove himself worthy in the family. In this fanfiction, their interactions drive the story forward as they are the central focus.
One possible plot could be that they run away from the chaos of Gotham. Maybe they're tired of the constant fighting and the shadow of Batman. They might start a journey to find a new place where they can define themselves outside of the Bat - family drama. Along the way, they could face various challenges that test their relationship, like dealing with criminals who are after them because of their connection to Batman.
They might initially clash due to their different personalities and past experiences. Damian is more disciplined and trained from a young age, while Jason has a more rebellious streak. In the fanfiction, they could start off fighting but then gradually come to understand each other as they realize they both have a common goal of protecting Gotham in their own ways.
Maybe a scenario where they start off as rivals in the fanfiction. Jason resents Damian for replacing him in a way, and Damian sees Jason as a wild card. But as the story progresses, they come to understand and respect each other's values.
One great fanfiction is 'The Bond of the Bat Brothers'. It really delves into their complex relationship, showing how Jason's more rough - edged nature clashes and then meshes with Damian's headstrong personality. The author does an amazing job of creating scenarios where they have to rely on each other.
Initially, Jason and Damian might be reluctant to trust each other. However, as they face challenges on the run, like escaping from pursuers or finding food and shelter, they'd be forced to work together. This would gradually lead to a deeper understanding. Damian might learn from Jason's more street - smart ways, and Jason could gain a new appreciation for Damian's tenacity. Their relationship would transform from one of suspicion to a sort of brotherly bond.