The exuberant young OPA fighter who helps Miller clear the Nauvoo, then joins him on the dangerous Eros mine mission.
Diogo has become part of Miller's loose Tycho orbit after surviving the Thoth assault. During the OPA seizure of the Nauvoo, he leads the deployment of a nonlethal sedating gas against Mormon resisters and helps search out stowaways and saboteurs. His casual efficiency makes the operation possible without the massacre the outnumbered security team fears.
He then ships with Miller aboard the Talbot Leeds, where his optimism is comic but sincere. He celebrates Mars's reported destruction of Phoebe as proof that Mars might be on the Belt's side, while accepting that the hope may be more dream than alliance. He still saves Miller a top bunk and meets the lethal mission with youth's bravado.
Diogo is a very young, lean Belter with an exuberant grin and the casual style of Tycho youth. Off the assault he wears a meshwork shirt and fashionably cut pants, later adding bright red plastic decorations to his front teeth.
Diogo is Miller's young OPA companion, bringing practical Belt instincts and stubborn hope to an operation older people understand as nearly suicidal.