Tbh i headcanon that part of the reason Ed was so good at alchemy is bc he had a sibling. With siblings nothing is free. Equivalent exchange at its finest. I just traded half a bottle of soda for the use of my sister’s earbuds on the way home. She brought up the fact that she gave me a drink while I was laying on the couch two months ago in order to convince me to bring her snacks. The Gate of Truth doesn’t have anything on a younger sibling who wants something and did something nice for you a couple years ago