It could be a creature born out of chaos. This being might be drawn to the unique energy created by the meeting of Atreus and Calliope. It tries to consume their combined power, causing destruction in their path as they struggle to stop it from achieving its goal.
It could be another god who is jealous of Zeus' interest in Atreus. Maybe a god who feels that Atreus is an outsider and doesn't belong in their divine affairs.
One possible plotline could be that Atreus and Calliope meet in a magical forest. Atreus is on a quest, and Calliope is there seeking inspiration. They initially misunderstand each other but then gradually come to respect and help one another on their respective journeys.
In Atreus and Calliope fanfiction, the theme of cooperation is quite prevalent. They have to work together to achieve certain goals, whether it's saving their world or just getting through a difficult day. Additionally, the theme of self - discovery within the context of their relationship is often explored. As they interact more, they learn more about themselves and their capabilities, and this is beautifully depicted in many fanfictions.
One popular Atreus and Calliope fanfiction is 'The Adventures of Atreus and Calliope'. It focuses on their journey through a magical forest, facing various challenges together and strengthening their bond. Another one might be 'Atreus and Calliope: A New Beginning' which delves into how they start a new chapter in their lives after a major event in their world.
One common theme is loss. Since Calliope is no longer alive in the main story, many fanfictions deal with Atreus' sense of loss and how he copes with it regarding his sister.
One great 'god of war atreus and calliope fanfiction' is 'The Bond of Siblings' which beautifully explores their relationship. It delves into how Atreus remembers Calliope and the impact her memory has on his journey.
Maybe Atreus is on a quest and by chance stumbles upon Zeus. Zeus could initially be wary of Atreus but then realizes his potential. They might engage in a conversation about power and the future of the world.
It could be a cruel dog catcher. He's always on the lookout for stray dogs like Scamp. He sees Marinette trying to protect Scamp and tries to outwit her to catch Scamp. He doesn't care about the bond between Marinette and Scamp and is just focused on doing his job, which in this case, is seen as the 'bad' thing.
A new character could be introduced as the antagonist. For example, a powerful and greedy hyena who wants to take over the Pride Lands. When Mufasa and Simba meet, they have to team up to fight this new threat. The hyena might have some special powers or a large army of his own followers.
A Sith Lord who has been manipulating events from the shadows could be the antagonist. This Sith Lord might be trying to use Rey's connection to Anakin to bring about the return of the Sith in a new and more powerful way. He could be using dark side illusions to make Rey and Anakin distrust each other.