History
Pale Horse was one of the surviving members of the Order of the Glorious End after the performance of a ritual that summoned the cosmic entity of Death. However, she was subsequently kidnapped. Death's disappearance made dying impossible across the entire universe.
When Thanos and Deadpool investigated the disappearance of their mistress, they ended up in the base of the Order, the Dwindling Light. Pale Horse and the other remaining members of the Order engaged them in combat before discovering they also worshipped Death. The Order offered the two intruders all the information they could give in exchange for their deaths at the hands of Thanos as soon as Death was recovered.
The Guardians of the Galaxy arrived to the Dwindling Light soon after, to track down Thanos, believing Death's disappearance to be his deed. The Order helped Thanos and Deadpool get the Guardians off their back until they could escape and continue their search.[1]