After reading quite a bit of lore, you're right on the 'Kerafyrm was not made as a mate for Veeshan.' Kerafyrm was born as a result of two different colors of dragons mating - Lady Vox and Lord Nagafen. Their son was a monstrosity who was insane and wanted to blot out all life with its tremendous power. Veeshan, who was afraid that this creature would challenge her creation or even she herself, imprisoned Kerafyrm in the Sleeper's Tomb to be guarded by four warders of immense power. Lady Vox was imprisoned in Permafrost and Nagafen in Solusek B never to mate again.
When the Sleeper was awoken by the guild Conquest, Jaled`Dar's shade is heard to say he's succeeded in waking the Sleeper, although indirectly, for he is the one that attempts to lure mortals into the tomb to destroy the world and finally release Jaled`Dar into the afterlife. Lord Nagafen tells of the Sleeper being awoken and his immediate marriage to Vox as a result. Just clarifying.
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