The Death Eaters could still be the main antagonists. If Harry starts learning soul magic, they might see it as a threat and try to stop him.
There could be a hidden group of dark wizards who practice a corrupted form of soul magic. They might see Harry as a threat to their existence or their plans. They could try to either recruit him or eliminate him to keep their secrets safe.
The Death Eaters could still be the main antagonists. Even though Harry has this new connection to Lady Magic, the Death Eaters, loyal to Voldemort, would see him as a major threat to their dark plans and would continue to try to kill him.
The Ministry of Magic could also be antagonists. They are often very strict about magic use and might not approve of Harry's exploration of wandless magic. They could try to stop him, fearing that it would disrupt the established order of magic that is mostly wand - based. The Ministry officials might see Harry as a troublemaker and try to put him under surveillance or even arrest him if they think he's getting too powerful in wandless magic.
Maybe it could be an ancient magical being like a centaur. Centaurs are known for their knowledge of the stars and ancient magic. They might take Harry under their wing and teach him old magic that has been passed down through their generations.
It could be an older relative who was thought to be dead but actually has been living in seclusion, waiting for the right time to teach Harry about their family magic. This relative might have a vast knowledge of the family's magical traditions and spells.
It could be a group of dark wizards who don't want Harry to succeed in becoming a cursebreaker. They might be using dark curses themselves to cause chaos in the wizarding world, and they see Harry as a threat to their plans. So they try to stop him at every turn, whether it's by setting traps or sending out cursed creatures after him.
Obviously, Harry Potter is a main character as the title suggests. He is the one who is on the journey of learning wandless magic. Hermione Granger could also be an important character. She might be helping Harry research about wandless magic, using her vast knowledge from the library.
Well, he might use soul magic to communicate with the spirits of the dead wizards. It could give him an edge in battles as he might understand the essence of his opponents' souls.
The Thalmor could be great antagonists. Their strict control over magic and their anti - human beliefs could put them at odds with Harry. They might see his different form of magic as a threat to their power in Skyrim.
One possible antagonist could be a corrupt wizard in a high - ranking position in the Ministry of Magic's financial department. This wizard might be trying to cover up his misdeeds and would see Harry as a threat to his scheme.
In such a fanfiction, Harry might discover ancient spells that give him an edge in battles. For example, he could learn old defensive magic that can protect Hogwarts in a more powerful way than the existing spells. He might also use old magic to communicate with long - lost magical creatures that hold secrets of the wizarding world.