What are the consequences of Merlin changing the past in fanfiction?

One consequence could be an alteration in the relationships. For example, if he saves Sirius, the relationship dynamics between him, Remus, and the other members of the Order would be different. They might be more united and effective in fighting against the Death Eaters.

The entire world of the story could be altered. Monsters might be stronger or weaker depending on what he changes in the past. If he stops some key event that was related to a monster's origin, it could lead to a different power balance in the world of demigods.

Mordred could get angry and seek revenge. He might plot against Merlin later.

One consequence could be that Arthur becomes more aware of the threats around him. He might start to trust Merlin even more, seeing him as someone who truly has his best interests at heart. This could lead to Arthur relying on Merlin more in future situations.

It can also affect the anime's cultural transmission. Anime often contains rich Japanese culture. When translators change stories, some of these cultural elements might be lost or distorted. This could prevent the international audience from fully appreciating the original cultural context of the anime.

One consequence could be a change in the story's plot direction. New friends might lead you to different adventures or challenges in the cameo story.

Merlin could face exile. Uther may not tolerate having a magic - user so close to him.

He could face Morgana's distrust if she takes his secrecy the wrong way. Maybe she'll think he has other motives for hiding his magic from her.

In some fanfictions, Merlin might use his magic to change the past. For example, he could go back in time to prevent a certain event from happening that had a negative impact on Camelot. Maybe he'd stop an assassination attempt on Arthur or change the way a law was made that was unjust.

One consequence could be that purists might object. For example, those who are very familiar with Greek mythology might not like it if you change the name of Poseidon. However, it can also attract new audiences who might be more interested in a modern or unique take on the story.