Come to think of it
All of the Ralsei character development has been entirely optional, unlike all of Susie's development.
You have to ask Ralsei how he's doing when he wants you to talk to Susie
You have to go to his room in castle town
You have to tell him it's ok not to smile

It seems how far he comes as a person, how much he can see himself as a person, is all up to how much you care specifically.