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.
I'm not sure if there is a widely known 'beast boy totrued fanfic'. You could try searching on fanfic platforms like Archive of Our Own or FanFiction.net. They have a large collection of Teen Titans - related fanfics and might have something with a similar title.
The 'beast boy sad fanfic' could be a creative exploration of the character in a more vulnerable state. It may attract readers who are interested in the emotional depth of the character. It could also serve as a way to expand the existing narrative of the Beast Boy's story in the original source material. By focusing on his sadness, new aspects of his personality and relationships can be uncovered and developed.
One great 'Starfire x Beast Boy fanfic' is 'A Different Kind of Bond'. It shows their relationship developing in a really unique way. The story has a lot of heartwarming moments as they learn more about each other.
It could be Slade. Slade might manipulate situations to make Beast Boy look bad in front of his friends. He could spread false rumors or set up situations where Beast Boy fails, which would make Beast Boy angry at being wrongly accused and at the fact that his friends might start to doubt him.
Some interesting Beast Boy Beast fanfic ideas could involve time - travel. He could go back in time and meet his younger self, and through that encounter, he learns something important about his growth and development. There could also be a fanfic where he is the only one left in the Teen Titans and has to figure out how to carry on their legacy all by himself. This would really show his character's strength and determination. Additionally, a fanfic that explores his dreams and nightmares, and how his powers might be affected by his subconscious thoughts, could be really fascinating.
A 'beast boy x raven lonely beast fanfic' could be full of emotional depth. Since Raven often has a complex and somewhat withdrawn nature, and Beast Boy is more outgoing. In this fic, their dynamic might be about Beast Boy bringing out a different side of Raven. It could also involve some kind of adventure or situation where they have to rely on each other, especially when Raven is in her 'lonely beast' form which might come with its own set of powers and challenges.
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.