One common theme is the reaction to power. For example, when a character reveals a new level of power, how others in the story respond. This can range from shock to envy.
It has ended. The last chapters wrapped up the plot and brought the manhwa to a close. There might be spin-offs or related works in the future, but the main storyline is completed.
It's a story that involves intense battles among high school students. They compete in a martial arts tournament where they display their unique skills and powers.
There is also 'Highschool DxD: Rias' Reaction to Issei's Past'. This one delves into how Rias, one of the main characters, reacts to Issei's past experiences and secrets, adding a new layer of depth to their relationship.
A great 'God of War' reaction fanfic might explore the reaction of Atreus to his father's past deeds as they are gradually revealed. He could be shocked, angry, or even more determined to make amends for his father's wrongs. Also, fanfics could show the reaction of the enemies when they face a more strategic and less brutal Kratos. They might underestimate him at first, thinking he's lost his edge, but then quickly realize he's still a formidable foe.
I really like the 'god of highschool crossover fanfic' that involves a crossover with 'One Piece'. Imagine the 'God of Highschool' fighters sailing on the Grand Line. The fanfic might explore how their powers would fare against the Devil Fruits and Haki in the 'One Piece' world. It also delves into the different cultures and the idea of friendship and adventure in both worlds, which is really interesting.