Horus Aximand

Horus Aximand, Little Horus, captained the Fifth and sat the Mournival with a face that looked like a smaller Warmaster. That resemblance was a career until Loken ruined it with a scar on Isstvan III. He helped murder the loyalists there, including Tarik, and spent the rest of the war trying to decide whether the scar was a punishment or a gift.

He is not Hastur Sejanus. He was never the other Horus. He spent his life almost being him, which is a worse job than either. The Saturnine ambush on Terra is where the scar came due: a loyalist trap, a familiar face, an ending that finally made him specific.

Cthonia minted a gang-son. The Vengeful Spirit minted a lieutenant. Isstvan spent him.