Well, it's hard to say for sure without reading the whole fanfic. But Harry is the central figure. There could be some older, wiser magical beings that are crucial to the story. They could guide Harry in his new life as a lich or try to put an end to his existence. And then there could be some ordinary wizards and witches whose lives are affected by Harry's transformation, and they might also be considered main characters in terms of how they impact the overall plot.
The Lich King, Arthas, is central to the 'wrath of lich king story'. Then there are characters like Uther the Lightbringer who was Arthas's mentor and whose influence still lingers in the story. Sylvanas Windrunner also has her part to play, especially in relation to the undead and her own vendetta against the Lich King. And many other heroes from different races, such as Thrall from the Horde, contribute to the complex web of characters in this story.
Arthas is a main character as he is the Lich King. Tirion Fordring also plays a significant role. And there are other heroes from the Alliance and Horde like Jaina Proudmoore.
Well, in 'harry the lich fanfic', one interesting plot could be Harry's transformation into a lich and how he copes with his new undead state. Maybe he has to deal with the loss of his former humanity and the new powers that come with being a lich.
There is also a young mage who becomes an unexpected ally of the lich. This mage has his own motives and goals, and his relationship with the lich is complex. They both learn from each other in different ways. And then there are some powerful demon lords that play important roles. They are constantly in conflict or cooperation with the lich, depending on the situation in the story.
In 'Harry and Teddy fanfic', the two main characters are Harry and Teddy. Harry is the one who has been through so much in the wizarding world. He has a sense of responsibility towards Teddy. Teddy is a character full of possibilities. He's the product of a tragic event (his parents' death), and Harry's presence in his life is like a guiding light. Their personalities, Harry's wisdom and Teddy's eagerness to learn, are often explored in these fanfics, which makes for very engaging stories.
In some fanfics, there could be magical animals other than crows. For instance, a wise old owl that serves as a mentor to Harry. The owl could give Harry advice on how to deal with various situations, such as when he is facing a difficult choice or when he is in danger. These additional characters add more depth and variety to the fanfic stories.
Then there might be some souls that Harry has a special connection with. These souls could be recurring characters, each with their own backstory and personality, and their interactions with Harry would drive the story forward in different ways.
Harry is the central figure. But there could also be other students who become aware of Harry's situation. For example, Hermione might be a key character. She could be researching ways to either help Harry or deal with the consequences of his transformation. And then there could be a new character, perhaps a magical cat - keeper in the Forbidden Forest who has some knowledge about cat - like magic and can offer assistance to Harry.
There might also be other Autobots such as Bumblebee. Bumblebee could be Harry's friend, always there to help him out in tight situations. Maybe there's a human - Autobot liaison character who helps Harry understand the Autobots better. And let's not forget, there could be some antagonists from either the wizarding world or the Decepticons' side who play important roles in driving the story forward.
There might be a villain, perhaps a dark wizard who is jealous of Harry's unique druid abilities. This villain would constantly try to undermine Harry and his efforts to use his powers for good, creating a lot of conflict in the story.