Star Trek: 10 Disturbing Side Character Backstories
1. Guinan
Star Trek: Picard has given us a lot of insight into Guinan's past on Earth. In the Next Generation episode Time's Arrow, we learned that she even lived on Earth as early as 19th century, as her species, the El-Aurians, live extremely long lives and can even control their aging. It's implied that she was on Earth to hide from her father, but the true tragedy of Guinan's life wasn't her struggles on ancient Earth, or even her time in the Nexus in Star Trek: Generations.
Some time in the 23rd century, Guinan's home world was destroyed by the Borg, and most of her species was wiped out. Guinan was reluctant to share this information with anyone, even her closest friends, but when the Enterprise-D encountered the Borg in the episode Q Who, she finally told Picard.
The El-Aurians were one of the most powerful species in the galaxy before they were exterminated by the Borg. They have highly evolved mental powers that can sense disturbances in time, and they even have a strong relationship with the Q, able to summon a member of the Continuum in times of need.