Du'Rog was a Narn, a member of the Kha'ri who was humiliated by his political enemy, G'Kar. Du'Rog swore revenge, but decided to bide his time.
When he learned he was dying in 2258, he arranged for his assets to be liquidated upon his death to fund an assassin from the Thenta Makur to kill his old enemy. He left specific instructions that a final message from himself was to be delivered to G'Kar (which informed G'Kar he would be dead within 48 hours). He wanted G'Kar to know fear and pain before dying at an appointed hour. The assassin he hired was Tu'Pari, but he was unable to carry out his order.
Du'Rog died believing his revenge was certain, never knowing it never came to pass.
Notes
Du'Rog's sole appearance was in The Parliament of Dreams.