Kovu cares for his brother, but can also feel embarrassed by his actions, as shown when Kion pinned him to the ground and Kovu's voice contained disappointment when he revealed that they were related. Kovu does not approve of his brother's devious nature, and will not allow him to disobey their mother's orders.
It is likely Kovu misses and cares for his brother after his death.
Zira does not appear to care for her eldest son quite as much as she does her other children, as is evident by her lack of interest in anything he does. She seems to view him as somewhat of a failure and shows annoyance at some of his antics. She is barely phased when Kion tackles her son, merely wishing to continue her plan.
While it is not shown in The Lion Guard how she felt when Nuka died, Zira was indeed devastated by his death revealing that she actually did love her eldest son but never showed it. Nuka's death intensified her hatred of Simba and the Pride Landers. His death enraged Zira so much that she launched an attack on the Pride Lands in order to avenge his death.
Vitani cares for her brother, but can also feel embarrassed by his actions, as shown when Kion kicked him falling at the ground and she said, "Nuka, Nuka, Nuka" in a disappointed tone. She seems to think he is inferior to other members of the pride, but that doesn’t stop her caring about him. Unlike Kovu, she does not attempt to stop her older brother from making a fool of himself.
After Nuka’s untimely death, Vitani probably still cares for him.
Although never being told about Nuka, after Jasiri says lions have taken over her watering hole, he goes to resolve the matter only to be ambushed by Nuka, who attacks Jasiri who he attacks back and demands he let him go after Kovu shows up, showing great disgust at Kion for siding with a hyena showing he hates them.
He despises Kion for attacking him, and for not siding with his pride and shows great happiness when he thinks Kion is powerless for not being able to use his roar, running up to avenge himself only to be attacked by him again, showing that no matter what, he will always fight his enemies.
Nuka is cowardly, as seen when he admits he is scared when they were losing the fight and when he refuses to "play nice" with Jasiri and does not want to give back her watering hole showing his evil side which is the complete opposite of Kion.
As an offspring of Zira's, Simba banished Nuka to the Outlands with his family, making Nuka resent the King. It is uncertain whether or not, after the two prides joined and Nuka was killed, Simba’s opinions on the Nuka changed.
Nuka has a noticeable hatred for Jasiri, mainly due to her being a hyena. After running her clan out of watering hole, Nuka was quick to pounce on her upon return, before Kion stepped in. He remained disgusted at the idea of a lion working with a hyena, even after Kion suggested that they might be able to return to the Pride Lands.
When his mother took Kion away, Nuka grew restless and was willing to attack Jasiri. When she returned, Nuka feigned friendship with her.