A Dangerous Bond.

James is a character I haven't worked on in quite some time. Maybe you remember him? He's one of the DragonKnights.
Anywho, James did something... well, something stupid really. There's a mark on the side of each DragonKnight's neck. At normal, its a clear blue. However, there are different colors which mean different things. Red being the most concerning. Red is the sign of corruption.
There's a way to bond with a dragon, where your minds connect. You can share knowledge, lifespan, strengths and abilities. It makes a Knight, and Dragon much more powerful then before. However, such power can prove costly. For the bond to work correctly, both minds need to connect and live in harmony. However, if the slightest imbalance occurs, both minds will struggle for control and merge together, ripping apart both parties' sanity. The imbalance doesn't always happen immediately, and for James it happened at nightfall, when he walked alone.
Perhaps it was a moment of clarity which made him feel shame, or madness and confusion. Either way, that was the night he fled, not to be seen again by any of his comrades for quite some time.