Reminiscing the enemies that were defeated throughout Rex's journey, a fundamental lesson was learned. Albeit most of the time, standing on the side as a witness, it doesn't diminish the effect of their deaths that were eerily caused by fundamentally the same mistakes that made her reach this conclusion.
If faced with a serious problem, emotions are the number one enemy.
One needs to win against emotions first before being able to solve the problem at hand.
Just like Adhara, who often stood as a silent observer of their downfalls or arrived too late to lend assistance, Ryze shared a similar role. He primarily lingered in the background, offering little help while relishing the safety and privileges afforded by Rex.
Accompanying Delta is the only helpful thing he does.
Meanwhile, Rex who essentially took him under his wing was constantly in a lot of trouble.