so he was a Navigator of a lesser vessel that escorted the Massive around. one time his ship needed repairs and so a younger and shorter Zeb came to help. but he messed up and caused an explosion that sizzled part of Ligu's face off as well as most of that antenna. Ligu flew into rage and tried to kill Zeb before his pak forced him unconscious to limit the damage to his face.
after Ligu got somewhat repaired, he went to search for Zeb to enact his revenge, but to his surprise Zeb had come to him to try to make it up to him.
Ligu refused, insisting on killing Zeb, who politely declined.
so Zeb got himself installed on Ligu's ship so he could continually try to make it up to Ligu, to the latter's chagrin. no killing each other was a rule on that ship unfortunately, so Ligu just had to put up with Zeb existing.
for now