Kalthea was Queen of an unnamed culture in an unnamed planet. Her civilized people were attacked by "barbarians" from the same world. While her soldiers fought, Kalthea remained unarmed in the battlefield. Her standing defiantly among the bloodshed instead of fleeing to safety supposedly served as an inspiration to the troops. Uatu the Watcher was observing the battle and felt attracted to her.
Kalthea's forces were eventually overwhelmed and Kalthea was about to die. Breaking his non-interference oath, Uatu apperared on the battlefield and frightened the barbarians away. Kalthea thanked him and proposed marriage to her savior. Uatu had to regrettably decline because it would mean abandoning his post as a Watcher. She remains his only known love interest.