[@Byte] it's up to you really. Different nations and states have different ways of going about it. The only nation with a formal standardized system would be the Kovosian Empire and it'd look something like this:

A whole bunch of kids from wealthy and noble families would get sent to an academy to start their training, start em young at say 12 years old. Those who can't awaken by the age of 18 get washed out. Mages get sent to a different academy, but it's the same kind of deal; only the top performers make it through.

Then they get taken to one of several dragon breeding sites and are given a year to successfully bond with one. These dragons would already be trained to a degree to respond to commands from an experienced rider, but novices will be outright ignored unless they do something to stand out. This could be anything from trying to ride a dragon when the opportunity presents itself, or picking a fight with one and winning, or simply putting on a display of magic.

Whichever way it happens, anyone who successfully bonds with a dragon without getting maimed or killed in the process then go on to learn how to fly, practice drills, tactics, formations, communication techniques such as hand signs or whistles, and of course fighting from dragonback. Learn all that and you're officially a dragon rider of the Empire.

Mind you this is the kind of enemy your character will be facing, so it's likely that each fighter of the Alliance could be stronger individually to make up for the difference in their quality of training as dragon riders. That is to say while the Empire might have better soldiers, the Alliance could have better warriors if that makes sense.

[@Psyker Landshark] I'm looking forward to it!