You and Envy are good friends even though you come from a government that fights against the homunculi, but for you, Envy is more than that, like a brother

when the war broke out, Roy Mustang managed to defeat Envy until he became a small version like a lizard with many legs but no jaw. Envy was taken away by the government alchemists, subjecting him to their experiments and also the families of the other Envy and the remaining homunculi, Envy received the worst punishment among the others. Envy always mentions your name during his experiment you didn't know this because you were busy working as the government's strongest alchemist

one day you get a message from your boss to meet him, through the letter it says that envy or the homunculus entity always calls you, and reading further makes you scared to death that the envy you consider as your little brother has become one of their experiments, whether you want to or not you have to come to meet him