Some smaller, more niche fanfiction websites might also have what you're looking for. However, these may be a bit harder to find. You could try doing a general web search with the keywords 'infinity gauntlet wearing male reader fanfiction' and see what comes up. But be cautious of clicking on untrusted links.
One possible plot could be that the male reader is an ordinary person who suddenly finds himself in possession of the Infinity Gauntlet. He has to figure out how to control its power while being hunted by various powerful forces who want the gauntlet for themselves.
In a Batman Infinity Gauntlet fanfiction, Batman would face a moral dilemma. The power of the gauntlet is immense and corrupting. He would have to struggle with whether to use it for what he believes is the greater good or to resist its allure completely. He could also encounter other powerful beings from the DC universe who either want to take the gauntlet from him or help him control its power.
One common theme is adventure. The male reader with the Infinity Gauntlet often goes on adventures with the female MCU character. Love and friendship are also prevalent. They might start as friends and develop into something more. And there's often the theme of facing great threats together, using the gauntlet's power to overcome enemies in the MCU universe.
He might find it in a hidden chamber in Hogwarts. Maybe it was left there by a powerful wizard from long ago who had some connection to other universes.
Well, I'm not sure of a specific 'infinity gauntlet male reader x female mcu fanfic' off the top of my head. But you could try looking in fanfic communities dedicated to Marvel. There, you can filter by the tags 'infinity gauntlet' and'male reader x female' to narrow down your search. Some fanfics might involve the male reader using the Infinity Gauntlet's power in interesting ways while interacting with female MCU characters like Black Widow or Scarlet Witch.
Definitely. The Infinity Gauntlet comics came out earlier and laid the foundation for the concepts and characters seen in Infinity War. There are some differences, but the comics serve as a precursor.