There are several 'Heart of a Champion Fanfic' that are really good. Some explore the relationships between the characters in the context of the championship world. For example, how friendships are tested and strengthened during the tough competition. They usually have detailed descriptions of the sports events and the emotions of the characters involved.
I'm not sure exactly as I haven't read the novel. But usually in a novel titled like this, there is likely a protagonist who is striving towards a goal. It could be an athlete, a student, or someone in a competitive field.
The main theme could be about perseverance. In many novels with such a title, the characters often face numerous challenges and they have to keep going, showing that they have the heart of a champion, which is the will to succeed no matter what.
Well, it often focuses on the idea of a champion, which can add a new layer of excitement. In the Harry Potter world, the concept of a champion is already thrilling, like in the Triwizard Tournament. Fanfics with this in the title might explore different aspects of being a champion, such as the training, the pressure, and the glory.