UCHIHA SASUKE // one of the lone remaining Uchiha, Sasuke was entrusted to Mayuri when he was taken into the custody of the Omega at a young age. Since then, Mayuri has been experimenting on him in order to discover the infinite possibilities of the Sharingan and his bloodline.
UCHIHA MADARA // once a brilliant and powerful being in possession of immortality and the eternal Sharingan, Madara is a focus of much interest - lesser, now that he's been rendered blind. Even so, Mayuri uses him as his labrat, doing whatever he wishes with this washed-up product of NeoGenesis' bloody history.
NATAKU // a failed experiment who Mayuri discarded soon after his creation, who was soon after taken under the wing of Flemming.
WILLIAM FLEMMING // fellow scientist and researcher who interests Mayuri for his technological know-how. They've made collaborations several times in the past. Despite this 'camaraderie,' they keep each other at arm's length in order to avoid discussions regarding their differing views regarding 'emotional attachment' to their patients (or Mayuri's lack thereof).
"CROW" SENJI KIYOMASA // a muzzled dog. Crow is interesting for his ability to manipulate his own blood as a weapon; Mayuri keeps him under a tight leash and conducts experiments on him at his will. Quite meddlesome.
SIARNAQ // a product of the aforementioned collaborations with Flemming. Mayuri lost interest in him along ago.
TERRY MCGINNIS // another collaborative work with Flemming - mostly for usage of his suit. While Mayuri isn't directly responsible for his creation, he is under his guardianship and is used to collect interesting specimens under the anonymity of his other persona.