His duties were the same as other keepers of his planet, which was to lure in and capture aliens to run tests on them.
During the First Shadow War, his people were attacked by the "Dark Ones", when they were refused to allow a base to be built on their world. The Dark Ones released a strain of the same plague that infected Earth. His people studied the plague virus for three years before deciding to put their entire race into suspended animation. One person was brought out of suspended animation to take care of the machines and continue the tests on the aliens. 500 people had died in that service by 2267.
Kulan studied the records on the Excalibur and contacted Captain Matthew Gideon to discuss finding the cure. Gideon was repulsed by the idea of sharing information at the cost of innocent lives, so he destroyed the control mechanism.
Since Kulan had been awakened for a year and a half, his remaining lifespan was estimated to be only 6 months. Since no cure was discovered by this point, it is likely he died in September 2267.