Have probably kept close to a dozen of the Jack Dempsey's over the years and do not consider adult Dempsey's to be very shy. Grouchy would be my description, and as these fish reach adult size,I would be hesitant to place finger's in the tank.
Have had those that would take bits of krill,silversides,and earthworms from my hand but if it is tricks and handfeeding that I was interested in, I would purchase a puppy.
I try to keep my hands out of the aquarium as much as possible due to how easy it is to forget where the hands have been. Is easy to introduce,soap,perfumes,cologne
hand lotions,etc to the enviornment the fish lives in and thus cause the sickness or death of the fishes.
I am always a bit put off by those who want to or do,,, hold the fish ,pet the fish,or tease the fish with foods .
A dog or a cat would be much more desireable in my opinion.