Well, in general, a fanfic about Beast Boy's animal urges might explore how his ability to transform into animals affects his instincts and behaviors. It could show how he has to deal with sudden animal - like impulses in a human world or among his superhero friends.
To write a good 'beast boy's animal urges fanfic', you need to understand the nature of animals. Since Beast Boy takes on their forms, study their behaviors and instincts. Incorporate those into his character when he has the urges. Also, develop a strong plot around how he copes with or succumbs to these urges. For example, if he has the urge of a nocturnal animal, how does that affect his relationships with his friends who are active during the day? You can also use vivid descriptions to bring out the animal - like sensations he experiences. And don't forget to give him a character arc related to these urges, whether it's learning to control them or finding a new way to live with them.
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.
He might gain the power of enhanced healing. So not only can he transform into different animals, but if he gets injured during a fight or accident, he can heal himself much faster than before. This would make him even more of a formidable hero in the fanfic's story line.
In a Marvel fanfic, Beast Boy could have a complex relationship with the Inhumans. His ability to change forms could be seen as both a threat and an asset. He might have to prove himself to them. Also, his connection to nature could be explored in relation to characters like Black Panther who also have a strong connection to a certain aspect of the world.
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.
One possible story could be that Raven, who is usually reserved, decides to surprise Beast Boy on Valentine's Day. She might make him his favorite vegan treats and write a poem for him using her magic to make the words float in the air. Beast Boy, being his energetic self, would be overjoyed and probably shapeshift into a cute little animal to show his affection back.