Warhammer 40k - Horus Heresy Short Story - Luna Mendax by Graham McNeill

On Luna, Garviel Loken has become a recluse. His mind has not fully recovered from the horrors he witnessed on Isstvan III, and, after returning from his failed mission to Caliban, he has ignored Malcador's summons and devoted himself to restoring a garden in a forgotten dome of the Somnus Citadel. While waging an aggressive "war" on the aphids plaguing the garden, he is hailed by an unexpected visitor: Tarik Torgaddon, slain months ago on Isstvan III. Torgaddon cheerfully remembers being killed, yet insists he is there on Luna.