i learned my freshman year of college that if you take the end of a hairbrush/makeup brush/anything stick shaped and you press it against the hickey really hard and twist it for a while, it’ll help disburse it and mine were always gone within a few hours. don’t rely on makeup if you don’t have color correction or heat protection
honest to god a warm fork/metal whisk. warm it in some water, and put some lotion on the skin so you're cutting out the friction and irritation when using a metal fork. it'll help disperse the blood sitting on the skin. sometimes if its super dark it will take only some of it, but at least its lighter so covering with makeup is easier.