In some fanfictions, Aithusa could play a role in Merlin's discovery of more of his powers. Since dragons are so closely tied to magic in the Merlin universe, Aithusa might show Merlin a new aspect of magic that he was previously unaware of. This could be through some sort of magical vision or by guiding Merlin to a place full of ancient magic.
One popular 'Merlin raises Aithusa' fanfiction might be on Archive of Our Own. You can search for tags like 'Merlin', 'Aithusa' and 'raising' to find relevant stories. Some fanfictions in this theme could explore Merlin's magical bond with Aithusa and how he teaches the young dragon about the world of magic and Camelot.
They could have adventures where they explore ancient magical places. Maybe they find a long - lost magical artifact that has the power to change the fate of Camelot. Merlin, with his knowledge, and Aithusa, with its dragon abilities, would be a formidable team in such quests.
One common theme is friendship. Since Merlin has a special connection with Aithusa, fanfics often explore how their friendship grows and evolves. For example, they might start off as cautious allies and become true friends over time.
There is a fanfic called 'Aithusa's Growth and Merlin's Role'. This one delves deep into how Aithusa develops over time and Merlin's influence on that growth. It shows a very different side of their connection compared to what we see in the original series. The author does an amazing job of creating new scenarios and emotions within the world of Merlin and Aithusa.
I'm not sure of a specific fanfiction for this scenario off the top of my head. But you could try searching on Archive of Our Own. There are likely some great stories out there where Gwaine witnesses Merlin hatching Aithusa.
One interesting Merlin Beauty and the Beast fanfiction could be one where Merlin has the role of the 'beauty'. He might use his magic in unique ways to break the curse, like instead of just relying on love, he uses his knowledge of ancient spells. Another could be a story where the Beast is not a typical monster but a powerful sorcerer who was cursed and Merlin has to help him regain his human form while also dealing with the political unrest in Camelot at the same time. And there might be a fanfic where the Beauty and the Beast story is set in an alternate version of Camelot, with different characters taking on the roles and Merlin being the key to solving all the mysteries and saving the day.
In some fanfictions, Merlin's scar reveal could be part of a prophecy. For example, the scar is a sign that Merlin is the 'chosen one' to save Camelot. As the scar is revealed to the court, there is a mixture of fear and hope among the people, and Merlin has to prove himself worthy of the prophecy.
In some fanfictions, Arthur saves Merlin from a magical creature that has been sent specifically to target Merlin because of his powerful magic. For example, a dark wizard sends a shadow demon after Merlin, and Arthur, with his courage and swordsmanship, manages to slay the demon and save Merlin. This often leads to a deeper bond between them as they realize how much they mean to each other.
One interesting Arthur courts Merlin fanfiction could be one where Arthur discovers Merlin's magic in a very unique way, like during a battle when Merlin has to use his powers openly to save Arthur. This creates a whole new dynamic between them as Arthur has to grapple with his long - held beliefs about magic and his friendship with Merlin.
There are fanfictions where the world of 'Harry Potter' and the legend of Merlin collide. For example, a story might have it that the Sword in the Stone has a connection to the Sword of Gryffindor. Merlin, being the powerful wizard he is, reveals this connection to Harry and together they unlock a new level of magic that can defeat the dark forces. This kind of fanfiction often plays with the rich mythologies of both universes, creating a really engaging read.