Merlin might become more confident as Harry Potter. In his past life, he was often hiding his magic, but as Harry, he can be more open in the wizarding world. So he could be more assertive in dealing with challenges.
If Merlin is reborn, it would likely shift the power balance significantly. His knowledge of ancient magic is vast. He could potentially teach new spells and techniques to the younger wizards, giving them an edge over the dark forces. For example, he might introduce powerful defensive spells that could protect Hogwarts better than the existing ones.
If Merlin died in the fanfiction, it could trigger a series of tragic events. The balance of power could tip, and the villains might seize the opportunity to attack. It could also bring out hidden strengths in the remaining characters as they try to cope with the loss.
Well, perhaps Merlin's reborn identity as Harry Potter means he has an innate understanding of certain things. He could be able to see through Voldemort's plans more easily because he has seen similar dark wizards in his past life. Also, his relationships with the other characters like Hermione and Ron would be different. He might be a mentor - like figure to them, guiding them with his centuries - old wisdom.
One idea could be that Merlin is reborn as a student at Hogwarts. He could use his ancient magic knowledge to solve some of the mysteries that even Dumbledore has trouble with. For example, he might be the key to understanding the true nature of the Chamber of Secrets in a way that no one has thought of before.
Perhaps some of the snooty nobles who look down on Merlin and constantly try to get him into trouble. They could be making fun of his clumsy ways one too many times and he just snaps and hits them with a shoe. It would be a moment of satisfaction for the readers who don't like those arrogant characters.
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.
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.