Maybe a plot where Merlin discovers a prophecy that only Escanor can fulfill, but it requires him to sacrifice something dear to him. They embark on a journey to find a way around the sacrifice while also falling in love along the way. There could be many challenges like facing ancient guardians and deciphering cryptic riddles.
One interesting plot could be that an old magic starts to affect the Seven Deadly Sins, causing them to turn on each other. Merlin and Escanor are the only ones immune. They have to work together to find the source of the magic and stop it. During this time, they realize their feelings for each other are deeper than they thought as they rely on each other for survival.
A plot could be that Escanor and Merlin are tasked with training a new generation of knights. They have different teaching styles, with Escanor focusing on physical and mental fortitude, and Merlin on magical abilities. This leads to some humorous and also some tense moments as they try to work together.
One great fanfiction is 'The Sun and the Sorceress'. It beautifully explores the relationship between Escanor and Merlin. It delves into how their different powers and personalities interact. The story has some really heart - warming moments where Escanor's pride is shown in a new light in relation to his feelings for Merlin.
One great fanfiction could be titled 'The Unseen Bond'. In this story, Merlin and Escanor's relationship might be explored in a world where they have to overcome a new threat to the Seven Deadly Sins. It could show how Merlin's magic and Escanor's strength combine in unique ways. Maybe there's a scene where Escanor in his 'The One' form is protecting Merlin while she casts a powerful spell that could save them all.
Another idea for the fanfiction could center around their relationship. Perhaps it explores how Merlin has always been intrigued by Escanor's duality - his meek self at night and his powerful self during the day. It could show how they gradually develop a deeper understanding and respect for each other, which might even turn into a romantic relationship over time.
Their personalities. Escanor's pride and his noble nature contrast with Merlin's mysterious and often calculating ways. When writers bring these two personalities together, it creates a lot of tension and potential for character development. For example, Escanor might be forced to look beyond his pride when dealing with Merlin, and Merlin might open up more because of Escanor's straightforwardness. This makes for great storytelling.
Love and loyalty are also big themes. The relationship between Escanor and the OC can range from a deep friendship to a romantic love. In some fanfictions, the OC will be fiercely loyal to Escanor, even in the face of great danger. It's also common to see the theme of self - discovery. The OC, through their interactions with Escanor, discovers more about themselves, their abilities, and their place in the world of the seven deadly sins.
One idea could be a crossover where Naruto's world is invaded by the forces of the Seven Deadly Sins and Merlin from that universe has to team up with Naruto to stop them. Naruto's powerful jutsu and Merlin's magic could create some really interesting battle scenes.
One idea could be an OC who is a hybrid of two of the deadly sins, like pride and envy. This OC could struggle with the internal conflict of these two powerful emotions. For example, being envious of the power of other characters while also being too proud to admit it or ask for help. Another plot could be an OC who is on a quest to redeem the Seven Deadly Sins themselves, believing that they can be reformed. This would involve the OC facing many challenges and having to understand the true nature of each sin.
One great piece of fanfiction could be 'Escanor's Unlikely Bond' where the OC has a unique backstory that ties in well with Escanor's pride. The OC might be a mage with a hidden power that only Escanor can help unlock, creating a really interesting dynamic between them.
First, establish a common threat. For example, an ancient evil that can only be defeated by combining the unique powers of Naruto, Merlin, and the Seven Deadly Sins. This will force them to work together.