In a fanfiction plot, the Hydra experiment might accidentally create a hybrid of two Avengers' powers. This new entity is confused and out of control, and both Hydra and the Avengers are trying to get it on their side. The Avengers want to help the entity understand and control its powers, while Hydra wants to use it as a weapon. Meanwhile, the original Avengers are also dealing with the moral implications of this new creation.
Well, a possible plot could be that the Hydra experiment was actually a cover - up for a much larger and more sinister plan. The Avengers discover that the experiment was just the tip of the iceberg and they have to race against time to stop Hydra from unleashing something far worse. It could also be interesting if the experiment somehow gives an ordinary person the ability to see into the future, and that person becomes a key figure in the battle between the Avengers and Hydra.