I have 2 black cats who are litter mates, and except for being talkative, they have nothing else in common. One is rail thin with short hair, the other weighs 19 lbs and very long hair, fatty comes and says hello to everyone who comes in the house, and skinny hunkers under the stairs. My free advice (worth what you paid for it!), next vet trip- don't put out the box where they can see it, have it ready on top of the washer or other torso-height surface, pick up cat as you normally would, but so they can't see the box, carry them to it, and shut the door before they know what happened. Works for me anyway. My big fluffy fellow used to yowl on the way to vet, and if I cover his carrier well so he can't see out, he does almost the whole trip quiet. Will follow you now.
Thanks for this great advice. Following you back!