What is this behaviour?

Trevor has issues with food that is not "fixed." For example, this morning, Trevor and Devin were eating slices of cheese. I gave Trevor a fixed slice (whole) because I know that's how he likes it. I folded Devin's in quarters because I think that's a little less messy. When I gave Devin his cheese, he was delighted, and it was cute. I laughed, Trevor laughed, and then, Trevor asked me to fold his cheese, too. I did, because he asked for it. He took one bite, and then suffered a meltdown because the cheese was not flat, and it was in four pieces. He cried and cried and cried. I refused to get him more cheese, because I didn't want to give in. He eventually got more cheese, but what is this behaviour? Last night, we had mac and cheese with hot dogs. Trevor refused to eat the cut up hot dogs, picking them out of his mac and cheese. Instead, he asked for whole hot dog.

He also still has issues with throwing food out. In fact, last night on the way home, he asked what we were having for dinner. He wanted "leftovers". I didn't have any, so I made mac and cheese and called it leftovers.

I don't understand my little man.