Perhaps they start off as rivals at first. Bruce might be a bit suspicious of Barry's powers and his more light - hearted approach. But as they get to know each other better, they realize they can learn a great deal from one another. Barry could teach Bruce to loosen up a bit, while Bruce could show Barry how to be more strategic in his superhero work.
In the fanfiction, they could also cross over into each other's worlds in unexpected ways. For example, Barry could accidentally end up in an alternate version of Gotham where things are very different. Bruce would then have to help him navigate this strange new place while also dealing with the local threats. And through this adventure, they could form a deep and lasting friendship.
One idea is that Barry discovers a time - related threat that has the potential to erase Bruce Wayne's past, which in turn would change the present Gotham City. They have to race against time (literally for Barry) to stop this threat. Another could be that a meta - human is stealing high - tech equipment from Wayne Enterprises and using it for evil purposes. Barry and Bruce work together to track down this meta - human and retrieve the stolen tech.
One possibility is that Thomas Wayne Batman comes from an alternate timeline. He meets Bruce Wayne in the current timeline and shows him a different way of approaching crime - fighting. Maybe he has more brutal methods, which causes Bruce to question his own more restrained approach. They could then learn from each other and create a new, more effective Batman strategy for Bruce's Gotham.
Well, there could be an epic battle. Maybe the Justice League is facing a powerful enemy and Barry Allen, with his super - speed, arrives just in time to turn the tide. He could use his speed to disrupt the enemy's attacks and create opportunities for the other members of the Justice League to strike.
Well, in this fanfiction, there could be an epic showdown against a common enemy. The Justice League might initially be skeptical of Bruce Wayne's methods, but then they come to respect his strategic mind.
Well, they might start by comparing their high - tech gadgets. Tony would show off his Iron Man suit with all its amazing features, while Bruce would talk about the tech in his Batmobile and other gear. Then, they could end up working together on a project to fight a common enemy, combining Stark's genius in energy and robotics with Wayne's skills in detective work and combat strategy.
In such a fanfiction, they might start by sizing each other up. Bruce would be intrigued by Tony's high - tech gadgets and playboy lifestyle, while Tony would be curious about Bruce's dual identity and his more brooding nature. They could end up collaborating on a project, perhaps something to do with improving Gotham's infrastructure using Stark technology.
Well, one key plot point could be how Bruce Wayne first comes to the decision to adopt Barry Allen. Maybe Barry is in a tough situation, like being an orphan or in danger, and Bruce's sense of justice and his own orphan past drive him to take Barry in. Another plot point could be how Barry adjusts to living with Bruce. He might struggle with Bruce's strict rules and training regimens at first, but gradually come to understand their purpose. Also, there could be a plot point where Barry discovers his super - speed abilities while under Bruce's care, and Bruce has to figure out how to help Barry control and use his powers for good.
One possible plot could be that Thomas Wayne somehow time - travels to the present where Bruce Wayne is Batman. Thomas could initially be shocked at how Bruce has turned out, but then come to understand his motives. He might offer some old - fashioned wisdom that helps Bruce in his fight against crime.
The adoption would have a profound impact on the DC Universe. Firstly, in terms of storylines, there would be a whole new set of arcs centered around Bruce and Barry's relationship. For example, how Bruce helps Barry master his powers while also dealing with his own issues. Secondly, it could change the way the superhero community views family. If Bruce can successfully adopt and mentor Barry, it might inspire other heroes to take in proteges. And finally, it could affect the balance of power in the universe. With Barry having Bruce's support, he could become a more dominant force in battles, which might force villains to rethink their strategies and alliances.
Well, in this fanfiction scenario, their pregnancy could bring out new powers or abilities. Maybe the baby has some sort of meta - gene that starts to affect Caitlin while she's pregnant, giving her new ice - related powers. Barry might also find that his connection to the Speed Force is altered because of the new life growing inside Caitlin. And as they prepare for the baby, they could start to train a new generation of heroes within the Flash team to help protect their family in the future.