Question: Why did Jelani keep slaves after becoming king? And shouldn’t the fact he kept slaves mean that Azura logically should have him on her shitlist?
That's a good question, but to explain it properly I have to talk about the history of Uekoro for a second.
In ancient times, the Matuzan cities we know today used to be totally separate kingdoms. Each had their own laws and cultures. Then, when Matuzu Kingdom rose to a Great power, all these little kingdoms were absorbed as cities/holds under its jurisdiction.
This means Uekoro used to be its own kingdom, and slavery was legal there. But when it was absorbed by Matuzu Kingdom, Matuzu said, "We don't like slavery in our great kingdom. You have to abolish it because you're making us look bad".
And Uekoro said "kiss my ass lol".
So in the end, they made a compromise: slavery was abolished for everyone in Uekoro...except the royal family. The Uekoran royal family (in this case, the Fanakas) could continue keeping slaves legally under Matuzan jurisdiction. To abolish slavery or not can only be decided by the Uekoran royal family, with a caveat: once slavery is abolished in Uekoro, it cannot be reinstated. This was part of the terms they agreed to with Matuzu Kingdom.
Slavery is a very longstanding tradition for the Uekoran royal family. Some family members throughout history disagreed with it, but they were not brave enough to be the ones to end it, because the rest of the family would have them by the throat. So, the old tradition continued in the palace while the rest of Uekoro progressed into more modern, sensible ways.
Okay, history lesson over! Now, on to your question...
As the Uekoran King, Jelani could certainly abolish slavery in his palace if he wanted to. Some of his relatives might be pissed, but the most dangerous and volatile of them (his mother) is dead, so it doesn't really matter.
However, Jelani carries a personal grudge against the palace slaves because of the way Itanya chose the Kaconenans over him. This "betrayal" cut him so deeply that it still hurts him decades later. His pain manifests as anger, and he takes his anger out on the rest of the palace slaves so that they may never "betray" him again.
Long story short, the palace still practices slavery because Jelani has emotional issues. See a freakin' therapist, dude...
During the 2 years they were together, Evan tried to convince Jelani to release his slaves many times. But it was a sensitive subject that made Jelani upset very quickly, so he was never able to push it too hard.
Azura, however...She has charisma and intelligence that Evan lacks. She successfully convinced Jelani to abolish slavery in his palace and replace all of his slaves with paid servants. This means that as long as Uekoro is under Matuzan jurisdiction, it can never reinstate slavery again. This was a huge historical event for the city, and Azura is credited for it.
Yes, as a slavekeeper, Jelani was on her shitlist. But Azura is too smart to just assassinate him and watch another slavekeeper take his throne...she went a hundred steps further and married the guy to influence his kingdom instead. Classic Azura move, honestly...
Evan does deserve a little credit though, because Jelani admits that it was his time with Evan that softened him up before he married Azura. Evan showed him what empathy and goodness looks like, Jelani respected him a lot, and wished to be more like him. So, I would say Evan and Azura both contributed. (Dr. Asha deserves some credit as well, because Jelani does mention that she's been counseling him through his grief about Itanya.)
An upcoming story pretty much opens with this scenario, so I don't feel like it's too spoilery. We'll explore this situation more when we get there!