Will and El are so into Mike that they are happy to date him together, and somehow that makes their "twinship" stronger so that Mike somehow feels left out even though they are obsessed with and dating him. Will and El are "The Best Friends" and Mike is "The Boyfriend." Mike is the center of both of their romantic/sexual attentions, but he struggles with not being the best friend anymore. Will and El are chill and can totally just sit around watching their boyfriend together, and Mike's like "hey, my eyes are up here."

The not-so twist, Will and El are NOT into each other because they are sorta-siblings and Will is gay. If the fic has sex they would not be engaging directly. Age at your discretion as long as they are season 4 or older.

Bonus if Mike has a Powers kink, and both Will and El have powers.