Yami and William have been friends for years. But they're both incredibly bussy captaining their own squads so a lot of times they have to spent time at each others bases in order to hang out.
And both squads just grow used the other captain's presense. They even welcome it. William brings some much needed calm and structure to the absolute choas that are the Black Bulls, while Yami brings fun and life into the Golden Dawn workaholics and get's them to relax on their down time.
And there isn't a single magic kight on either squad that questions it. That's just how it's always been and of course they'd want to spend as much time as possible with their partner, right?
So imagine their surprise when they learn that Yami and William are not actually in a relationship but are in fact really just close friends. Yeah right...
They hold a secret emergency meeting between the two squads, because honestly? That's just not an acceptable situation. These two are together. It might not have been true before but it sure as hell will be if they can help it.
And while all of them are formidable magic knights they are truely and absolutely down-right horrible matchmakers.
It starts innocently enough but over time they come up with more and more questionable ideas to make their captains realize their feelings for each other.
Charmy and Harmon organize several dinners for both squads to come together so Yami and William could spend more time with each other.
Mimosa secretly sends little letters and gifts to the captains pretending they are from each other.
One time during a party Vanessa threw for both squads David had the glorious idea to play poker against Yami and after taking all of his money in an impressive win streak, demands a different kind of wager. If Yami loses again he'd have to kiss William. Unfortunately, Yami actually somehow managed to win that round (it couldn't possibly be because he for once actually tried to lose, right?)
Even Gauche took part in it, hoping that if Yami got more wraped up in a relationship, he'd have more time to sneak off and visit his sister. Once, when he went and picked up Marie to show her around their base he asked her to mention William to Yami and how cute and romantic it'd be if they were in love, like a fairytale. After all nobdy could ever deny Marie a wish.
Klaus once read something about training the subconscious mind during sleep and Yuno therefore enlists Asta's help, claiming Yami would be more susceptible. And that is how Asta came to whispering into Yami's ear that he should confess his feelings while the captain was asleep. It ended after four nights with an Asta-shaped hole in the wall.
In any case, nothing they tried worked so they were all resigned to continue watching their painfully blind captains be oblivious to their own feelings. But if they are nothing if not resilient and they will go on and surpass their limits until those to are together as they should be.