One common theme could be the struggle for control. Loki, being in a state of 'heat' might have a harder time controlling his emotions and powers, and the Avengers would then have to deal with this new and unpredictable factor. Another theme might be acceptance. The Avengers might have to accept this new side of Loki and figure out how to work with him in this state.
His relationship with Thor would likely become more strained. Thor might not understand what's happening to Loki at first and think he's up to some new scheme. With the other Avengers, Loki might become more withdrawn as he tries to deal with his situation privately.
One way to find good 'Loki in heat and the Avengers' fanfiction is to join some Avengers or Loki - focused fan communities. For example, on Reddit, there might be sub -reddits dedicated to fanfiction. Members there often share and recommend their favorite works. You can also check the reviews and ratings of the fanfictions if they are available on the platforms where you find them. This can give you an idea of which ones are worth reading.
One idea could be Loki's struggle to control his 'in heat' state while trying to deceive the Avengers. He might have to constantly hide his true feelings and symptoms, which could lead to some comical yet tense situations.
This situation can be a catalyst for Loki's character growth. He may start to learn more about himself, his emotions, and his place in the Avengers' world. Maybe he realizes that he can't always rely on his usual tricks and manipulation. He might have to find new ways to deal with his situation, which could lead to him becoming a more complex and well - rounded character in the fanfiction.
One idea could be Loki's struggle to hide his condition from the other Avengers. He might be worried about how they'll react, especially Thor. Another plot could involve a character, perhaps a new Asgardian healer, trying to find a way to ease Loki's discomfort during this time.
Thor would be a likely candidate. Since he is Loki's brother, he already has a connection with him. Thor might be the one to convince the other Avengers to give Loki a chance and be the first to reach out and try to befriend him in this new situation.
Future Loki might interact with the Avengers in a cautious way. He knows their past opinions of him and tries to prove himself. He could start by sharing small bits of useful information. For example, he might tell Iron Man about a weakness in a new enemy's technology.
In this fanfiction, Loki might interact most with Hulk. It would be an interesting dynamic as Loki is a master of manipulation and Hulk is, well, the Hulk. Loki could either try to use Hulk for his own purposes, which would be very dangerous, or he could end up on the wrong side of Hulk's anger. But at the same time, it could also lead to some unexpected moments of understanding or at least a begrudging respect between them.