#naraku

i would daresay that kikyo is who he always feared the most, AND kagome for the power she could wield.

but most definitely all the courses of actions naraku EVER took in the entire story had to do with his feelings for kikyo and how he wished to get rid of them, and no matter how strong he managed to become after gaining the full shikon jewel, his feelings never went away. they were a constant even as he was dying.

now, sesshomaru was what he would've liked to become if he ever managed to become an actual, full demon. he coveted sesshomaru's power and everything he represented, therefore why he tried to absorb him once. but gradually, the stronger naraku got, the less wary or careful about sesshomaru he became as well.

naraku dropped the respectful speech for sesshomaru the moment the nearly full shikon jewel granted him a stronger body, so he definitely started feeling confident enough to not fear sesshomaru at all, jaken even points this out.

near the end of the story (chapter 500), he was still trying to use sesshomaru as a tool to get rid of inuyasha or have them both kill each other, toying with their dynamic, little concerned about any possible consequence at doing something like that.

if we compare that to how desperate naraku was for more than half of the story of getting rid of a portion of his body - bcs he couldn't bear the thought of being limited by the feelings that portion provoked - i'd say kikyo was a bigger concern for him and his motivation for everything (all bad things ofc (? but you get me).

naraku wished to murder kikyo bcs being able to get rid of her HIMSELF and by his own hand meant (in his head) she wouldn't have control over him anymore. he admits himself he went through All of That™ for the sole reason of getting rid of her.