Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Every PC's reason for leaving their home and race behind. The Human because Earth is destroyed, the Floran and Avian because they're outcasts, Hylotl because of the Floran wars, the Apex is escaping the torture and constant surveillance, and the Glitch would likely be executed for self-awareness.
Just listen to some of the more sad tracks like Mira and Tranquility Base. Doesn't make it any less awesome though.