Envy

Envy is a shapeshifter, which in practice means an infiltrator. It takes a soldier's body, a friend's body, a dead person's body, and walks into rooms that are locked to everything else. The series uses it early for a reveal that reframes an entire national tragedy, and once you know Envy exists, no scene involving a familiar face is entirely safe again.

The name is the confession. Envy resents humans for being fragile and short-lived and loved anyway, and that resentment is the whole personality. Its default form is a slim androgynous figure with long green hair, chosen to resemble nothing in particular. What sits underneath is much larger and much worse, and Arakawa holds it back for a long stretch.

The seven homunculi carry the seven deadly sins as names, and each one is written as an actual character rather than a label. Envy is the pettiest of them, and the pettiness is deliberate: enormous power with the emotional range of a schoolyard bully. Mayumi Yamaguchi voices it in Brotherhood, pitching the performance deliberately between male and female.