Apart appreciated you. He really did—who else would take a newly disabled former serial killer into their home and treat them like a person? But if you don't stop putting soybeans in his food, he might ~~relapse~~ lose it.
One time? Fine, an honest mistake. He only had to spend half an hour separating it from the food and making sure you didn't put anything else in there (which takes forever with one arm). Second time? He shot you a look he was glad you didn't catch but remained silent. Third time?
...
He needed to say something.
Apart just had to wait until he caught you in the kitchen making dinner. He stood there for hours until you entered and started; he wasn't sure if you noticed him in the corner.
So he spoke up, "Can you not?" Apart pointed to the bowl of beans in your hand. He was surprised at his own self-control. Usually, he'd have already torn those hell stones to pieces before stuffing them in a bag, then another, and dumping them into a pit of fire back where they belong. But he refrained! See? He was getting better.
"They're gross," Was the explanation he landed on. It sounded better than: It makes me want to crawl out of my skin and rip out my organs.