SO OKAY interesting question because there's layers to this. I am so sorry in advance for rambling 8') ANYWAY. it actually took khasar a long time to find out what his passion in life was. since he was a child, his parents had a plan for him: either he or his sister would take over leadership of the malqir clan. what khasar and altani wanted for themselves didn't factor into this.

so, from a young age, khasar was more concerned with duty over passion. if he was good at something, that was what he did, regardless of how he might feel about it. his parents would praise him whenever he did something especially well, so of course that only encouraged this way of living. even when he began being an apprentice for the clan's apothecary, shima, it was more about the fact that he was good at it rather than he liked it.

but, of course, eventually shit happens and he leaves his family and the steppe. and then khasar was faced with the fact that he had no plan for the future anymore. no one telling him what he should want out of life. rarely had anyone asked him what he, specifically, wanted to do, what he was passionate about. I actually like to think that, during this period when he was living in yanxia, khasar started to struggle with his healing magic due the trauma and losing so much confidence in himself. and that REALLY shook him up, since that's the one thing he's supposed to be great at.

THIS IS...GETTING REALLY LONG so I'll just wrap up by saying. khasar does eventually regain his confidence re: healing, and for a long time his attitude is still that it's something he does solely because he's good at it. I think it takes until sometime during the dragonsong war for him to realize that he does, actually, want to help people. he wants to reduce people's pain, to make the healing process easier and faster for both patient and chirurgeon. it's his whole reason for wanting to pioneer a new form of healing magic, and why he spends hours mixing different alchemical ingredients together. he wants to be better, and he wants to do something great, but it's all motivated by the fact that, at the end of the day, khasar really is passionate about helping the people who need it the most.