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.
Raven might be a bit aloof at first, but she would eventually try to use her magic to help him. She has a deep understanding of emotions and powers, so she would see it as her responsibility. Starfire would be overly concerned and would probably try to cook him all kinds of strange but nutritious meals to help him through it. Cyborg would likely try to analyze him with his tech, thinking there's some sort of mechanical or biological malfunction that he can fix.
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.
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.
Well, it could be about a character in the Naruto universe who somehow obtains the Heat Heat Fruit. Maybe they use its powers to fight stronger enemies. For example, they could create intense heat waves to defeat opponents in battles, just like how characters in One Piece use Devil Fruits' powers.
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.
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.
One possible plot could be a trainer going on vacation to a hot region in the Pokemon world. They might encounter Fire - type Pokemon that are more active in the heat. For example, they could meet a group of Charmander near a volcano. The trainer could then have adventures like helping a local Pokemon center deal with Pokemon that are overheated due to the extreme climate.
As I'm not familiar with this particular fanfic, the plot could be a million different things. It could be a love story where Beast Boy finds his true love. Or it could be an adventure where he discovers the true nature of his powers. It might also be a story about him growing and maturing, learning what it really means to be a hero, which is a way of becoming 'true' to his heroic self. Fanfics often take the original characters and put them in new and unexpected situations, so this one could be quite creative in its plot development.
A plot could involve an unexpected pregnancy. Beast Boy and Raven are in the middle of fighting some new villains when Raven discovers she's pregnant. This throws them off balance. They then have to figure out how to protect the baby while still being superheroes. They might have to hide Raven away for a while to keep her and the baby safe. Their relationship also deepens during this time as they face this new challenge together. Eventually, they have the baby, and it becomes a symbol of hope for the future in their world.