Although Kes keeps annoying and toying with Wheatley, her actions might have a very different effect on him then she thought:

While it may have been a worthwhile assignment, Kes was doing very little to excel at it. Wheatley was becoming more and more irate as she did the exact same thing, chamber after chamber. First, she would plant herself as far away from the pleasure-inducing button as possible and then she would start to toy with him by acting as though she was going to obey him but at the last minute change course and go right back into the corner. He had tried to retaliate by shaking the room up and treating her like an oversized labyrinth ball but she had simply used her handlebars to stop herself from rolling to the button.

All in all, it was taking an exceedingly extended period of time just to force her to produce that wonderful feeling and Wheatley was becoming furious. He had, after all, given her the best and most important assignment of all of them! It was completely in her power to give him that tremendous feeling and all she had to do was roll over to a little button and push it! He was practically giving her special treatment and she should be grateful, especially after that little episode in which she questioned his authority in front of all the other robots.

But there was another reason the core was starting to irritate Wheatley. Even though she purposely went out of her way to disobey him, constantly gave him lip, and consistently showed him the contempt she had for him, he was starting to get the vague and uncomfortable notion that she was starting to cause a strange feeling deep in his hull that he just couldn’t understand. He tried to tune it out by concentrating on how angry she was currently making him by becoming increasingly difficult but this had an adverse effect and made the feeling even stronger.

Of course, the thought had occurred to Wheatley that maybe she was starting to, in human terms, “captivate” him with her rebellious nature and difficult attitude but he quickly began to rationalize that she was merely an abnormal test subject and he had probably developed some sort of need to understand her.

In any case, while the two were on the fifth test, Wheatley found himself caught between irritation and the unnamed feeling he was experiencing.

“Love, to finish the test you need to get to the button!!” he snapped “Not around the button, not across from the button but ON THE BUTTON! God, why are you doing this to me?!”

Kes eyed him and rolled her optic.

“I mean it! I’ve given you the best job and never crushed you even when you deserved it!! But, still, you’re always disobeying me, always getting cheeky, always bloody irritating me!! I could’ve just dumped you with the rest of the cores into crap jobs like testing the turrets or poking the dead humans to see if they were alive! I could’ve even thrown you into the container with all the defective cores but I didn’t!”

She started to get a feeling of anxiety as she listened to him ramble on.

“But, no, I’ve always given you a chance, always gave you a job that was close to my lair, always let you get away with everything you did to try to sabotage me! Well, you know what?”

A claw was hoisted down and snatched Kes up roughly.

“Enough’s enough.”