Well, a popular one is 'The Scarlet and the Blue Devil'. In this fanfiction, Nightcrawler and Scarlet Witch start off as acquaintances but as the story unfolds, they find themselves drawn to each other in unexpected ways. Their powers complement each other in the story's action - like Nightcrawler's teleportation helping Scarlet Witch get out of tight spots. Another good one is 'Powerful Attraction' where the author focuses on the magnetic pull between their powers and personalities. It shows how they start to influence each other's way of thinking and acting. And 'Mystic Bonds' is a fanfiction that delves into the idea of a pre - ordained connection between them, perhaps something related to their mutant genes and how that could lead to a strong relationship.
One great Nightcrawler x Scarlet Witch fanfiction could be 'The Unlikely Bond'. It delves into how their different powers and personalities interact in a world full of chaos. Another might be 'Soul Connections' which focuses on a deeper, more spiritual connection between them that goes beyond their mutant abilities. And there's also 'A Meeting of Minds' where they team up to face a common enemy and in the process, discover new feelings for each other.
There are quite a few interesting ones. For instance, 'Red and Blue' which plays on their color schemes as part of their connection. The story has them cross paths during a mission and gradually realize they share a unique chemistry. Then there's 'Mutant Hearts' that explores their relationship in a more romantic light, showing how they support each other through difficult times. Also, 'Twisted Fates' is a fanfiction that throws them into an alternate universe where they are forced to rely on each other more than ever.