W'rkncacnter were imprisoned in stars, solar storms, and black holes. They are nearly impossible to control and their existence causes chaos. Maybe the W'rkncanter in the south American temple escaped and the Jjaro sent the traveler to contain it as it destroyed the earth. The Jjaro can move entire planets and have even created the s'pht (an alien cyborg race similar in appearance to the Hive and it's undead cyborg zombies). In Marathon, one escaping it's prison meant destruction on a cosmic scale with it's unbelievable and terrible power, which the travaler has given to you. Maybe some aliens, foolishly, are seeking out the power for themselves. (Even though they have no hope to control it).