/lit/ - Literature

Gonna repost since the rest of this board seems very hostile to fantasy lit: >>10525863

I'm not sure if I've given enough motivation for my main character's actions.

The character is a career thief and con-artist who is saved by a knight errant from being killed by some noble's guards over his latest scheme. The thief sticks with the knight, at first because he feels like he owes the guy and thinks such a do-gooder is just gonna get himself killed, and then over time because he legit believes in the knight's Don Quixote style chivalric ideals, eventually becoming his squire. They are one day ambushed by bandits, and the knight sacrifices his own life for the thief's. The thief, noting his remarkable "prince and the pauper" like similarity with the knight, decides to take on his friend's identity and fulfill his quest: to win a great treasure and gain the hand of his childhood sweetheart. He does this to preserve the memory of his friend, who he thinks died ignobly fighting common bandits that were only there to collect the thief's bounty. There's a few more bits and bobs to the whole thing, but I've wasted enough time, and someone could request more info.

tl;dr How much motivation is needed to realistically convince a con artist and gentleman thief to pretend to be Don Quixote, even at risk to his own life?