Yes, in some fanfictions, Merlin's sister might have special powers. For example, she could have the power of foresight like Merlin has magic but hers is more focused on seeing future events. This can add an interesting dynamic to the story as she might use this power to help Merlin in his quests or to avoid danger.
His water - controlling ability as a son of Poseidon could be enhanced with Merlin - like magic. He might be able to turn water into different shapes or even solidify it in more complex ways, like creating ice sculptures with magical runes on them. Also, he could have a new form of precognition related to Merlin's seer abilities, seeing not just the immediate future related to water or battles, but a more far - reaching view of events.
Another power could be the ability to communicate with magical creatures on a deeper level. Since Merlin was said to have a great understanding of all things magical, the heir in fanfiction might be able to gain the trust and cooperation of creatures like centaurs and unicorns more easily than others.
Another aspect of a fanfiction about Merlin uncovering hidden powers during training is how it affects his relationships. His new powers might make some people in Camelot, like Morgana, jealous. Or it could make Arthur more protective of him. Meanwhile, Merlin has to figure out how to use these powers for the good of Camelot without causing too much disruption. He might also have to face the fact that some of his new powers are not fully understood and could be dangerous if not properly controlled.
Merlin is often depicted with powers like magic over the elements. He can control fire, water, air and earth. For example, he can make fire appear out of thin air to protect his allies or to scare off enemies. He also has the power of divination, being able to foresee future events which helps him in guiding the heroes in the story.
Merlin's relationship with Arthur could become even stronger. They might have more adventures together and truly become equals in their fight for Camelot. Their bond could be tested, but in the end, it would only grow deeper.
Well, one prediction could be that Merlin discovers a new form of magic. Maybe he'll find an ancient spell book that has been lost for centuries. This could lead him on a journey to master this new magic, which might be different from the magic he already knows. He could face challenges along the way, like dealing with other wizards who are jealous of his discovery.
Hermione could inherit Merlin's powerful transfiguration abilities. Given that Merlin was one of the most powerful wizards in history, his descendant Hermione might be able to perform extremely difficult transfiguration spells with ease. Like transfiguring large structures or multiple objects simultaneously, something that is usually very challenging for most wizards.
Merlin's story isn't real. It's a combination of myths and imagination passed down through generations. There's no historical evidence to prove its authenticity.
One possible secret could be that Merlin is a powerful sorcerer from an ancient and powerful magical lineage. Maybe his family has a long - standing connection to Camelot that has been kept hidden.