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.
The fanfiction could explore the emotional side of their relationships. Jason might be dealing with his feelings of being an outcast from the Bat - family, and Damian could be struggling with his identity as both an assassin and a hero. Talia, having a deep understanding of both of them, could help them navigate these complex emotions. Their meeting could be a catalyst for self - discovery for both Jason and Damian, and Talia could be the guiding force in this journey of self - understanding.
In the fanfiction, it might show how Jason Todd and Damian Wayne grow to respect each other. Jason could teach Damian about the more gritty side of Gotham's underworld, while Damian could show Jason some of the advanced combat techniques he learned from the League. Talia could be the one who sets up situations for them to learn from each other. For example, she could create a scenario where they have to work together to stop a threat that she has uncovered.