Medieval/fantasy AU with dragons!! Because dragons!!! I just really like dragons okay?
Malec (and whoever else you wanna ship) Dragons, in order to thrive and grow, to even be born out of their eggs, need to bond with a rider. Not just any rider, but their rider. Riders however, only awaken upon contact with their dragon egg. The eggs naturally can't go looking for their riders, and the riders aren't aware of the eggs existence, so you have kinda the most desperate catch 22 ever. Which is why fate/mother nature/the old gods/whathaveyou built in a fail safe. A tribe was chosen to become the protector of the dragon eggs, and its people were gifted with magical abilities that would aid them in not only the protection of the eggs, but also in finding the riders. These people were called 'Warlocks'. The warlocks would bind themselves to the egg placed in their protection, this bond only ending once the egg hatched upon contact with its rider. The warlock would be immortal until that day, then a normal aging would presume, unless they bind to another egg. And so it worked for decades. Warlocks caring for the eggs and finding the riders, then either repeating the circle, or living out their lives in peace. Some even stayed with the dragon and its rider, forming the strongest of relationships. But as it always is, the promise of power breeds corruption. Other races (human, were creatures, fae folk,…) would attack the warlock tribe, try to steal the eggs, force the warlocks to make them the riders. (which, of course, the warlocks couldn't). Despite their powerful magic, the sheer volume of attacks and the overwhelming numbers pitched against them, killed many warlocks. And upon learning that being a rider couldn't be forced, the attacking parties destroyed many of the eggs. (After all, why give someone else this power if the attackers could not claim it themselves?) Over time, dragons and warlocks alike seemed more myth than truth.
Until Magnus Bane, the last warlock, having protected the last (insert number) dragon eggs for decades, finally gets a ping about their riders. (One of which, of course, is Alec.)