Shared health bar with dog

Hi! Im trying to make it so that I share a health bar with a dog... if he gets hurt, i do, if I get hurt, he does... same if I die or if he dies... kinda aiming to make this a hardcore, thought itd be cool yk... I already tried starting but there arent any results in the game... please dont make fun of me lol but I asked chatgpt and that thing is bad lol but ig it might be steering me in the rightish direction, it just doesnt know how to code yk..