Honestly I had my own idea for the knight character as well.

>Joining the circus he is afraid of the whole situation but keeps it inside always trying to appear tough but if someone got close to him and helped him feel less afraid he swears to keep them safe.
>As time goes on he would kinda latch onto this person almost to an unhealthy amount and if someone or something tried to cause any harm to them he'd respond violently.
>He's of little words only speaking to either that person he latched onto or anyone who he sees as harmful to that person's health.
>It gets a big obsessive and that's kinda his 'arc' so to speak is learning to be less dependent on just one person and giving them their own space and independence.
>During adventures you'll find him always next to his savior and if he's not he's looking to figure out how to get there as soon as possible.
>In the real world he was his parents caretakers in their old age and didn't have much of a social life since he would stay home taking care of them no matter what.