I'm not entirely sure as the title is rather unclear. It could potentially be about a group of children including Azuka and Sokka facing a dangerous beast and having to overcome their illness or some sort of handicap to defeat it.
The title 'azuka sokka children ill kill this beast fanfic' is quite open - ended. It could be a story where Azuka and Sokka are children with special powers. However, they are ill, which is a setback. But they must use their powers and work with other children to take on the beast. For example, perhaps the beast is a magical creature that has been causing chaos in their world, and they are the chosen ones to end its reign, even though they are sick.
Based on the title, it seems that Azuka and Sokka are likely to be the main characters. And also, there are some children involved, though we don't know who they are exactly yet.
Well, perhaps it could be about Beast Boy losing control over his powers and fully becoming the beast all the time. Maybe there's a curse or some dark magic at play that forces him into this state.
A fanfic could start with Ben being sent to the Kill la Kill universe through some sort of interdimensional rift. In this new world, he discovers that the Omnitrix can absorb the power of Life Fibers. This leads to a race between the heroes and the villains of Kill la Kill to either use Ben's newfound ability for good or to take it over for evil. Ben has to learn the ways of this new world quickly while also trying to find a way back home.
A possible plot could be them starting a family. Toph, with her earthbending skills, could build them a unique and secure home. Sokka would be the one teaching their children about the ways of different tribes and his combat skills. And they would have to face threats from old enemies who target their family because of their combined power.
One possible plot could be that Beast Boy gets angry because his friends don't trust his new animal form discovery. He feels isolated and lashes out at them, causing chaos in the Titans' tower. His anger might lead to him running away and getting into trouble in the city, where he has to face his emotions and learn to control his powers better while his friends search for him.
One possible plot could be that Beast Boy fails to save someone he cares about deeply. This guilt and the sense of loss could be the source of his sadness. He would then struggle to come to terms with his failure and find a way to move forward.
The plot could involve Raven feeling more isolated than usual and retreating into her 'lonely beast' form. Beast Boy, noticing this, decides to try and help her. He might start by just being around her, and gradually they start to communicate more. Eventually, they could face a common enemy together while Raven is still in that form, and their combined efforts lead to a stronger relationship.
Perhaps in the fanfic, Beast Boy going into heat could lead to him having a stronger connection to his animal instincts. He might start to have dreams or visions related to his animal forms. This could then lead to a story where he has to go on a journey to understand this new part of himself. His friends could be worried about him and try to follow, but he may want to do it alone at first.
The plot might involve Harry being mistaken for a threat when he first arrives at the Beast's castle. But then, as he shows his kind heart and magical abilities, he becomes an ally. He could introduce some of the magical creatures from his world to the inhabitants of the castle. For example, he might bring a house - elf like Dobby to help around the castle, which would be a very different experience for everyone there. And in return, he learns about the power of true love from Belle and the Beast's relationship.
One possibility could be that Beast Boy feels out of place. Maybe he's constantly overshadowed by the other Titans and decides he can be more effective on his own. He might leave to explore his identity outside of the team and find his true purpose in a world where he doesn't have to conform to the Titans' way of doing things.