OreSeur was a kandra of the third generation, under contract of first Kelsier, and later Vin.
OreSeur was the kandra that impersonated Lord Renoux. This position let him move supplies for the rebellion, and give Vin a cover and training as a noblewoman. OreSeur as Lord Renoux is "killed" by an Inquisitor during Kelsier's attack on the carts carrying the prisoners from the Renoux household. Kelsier is killed by the Lord Ruler during the battle. Given orders in the event of Kelsier's planned matrydom, that night OreSeur appears to Kelsier's crew in the guise of Kelsier, telling them that it is time to fight. He then appears to skaa all over Luthadel, encouraging them to rebel. The Lord Ruler is killed by Vin during that rebellion.
In the second book, OreSeur's contract has passed to Vin. He is tortured, killed, and digested by TenSoon, another kandra of the third generation (hired by Straff but ordered to follow Zane's requests) before he can take on the wolfhound body Vin has acquired for him.
- it is noted that TenSoon seems quite distraught after torturing OreSeur for information.