History
Nebula was the adopted daughter of Thanos the Just, a wise and noble peacekeeper from the moon of Titan. Unlike her sister Gamora who rejected her father's way and became a space pirate, Nebula remained loyal to Thanos and eventually became the Captain of Titan's Peace Force that watched over and protected the innocents of the galaxy. Her father meanwhile never lost hope for Gamora, believing that she would one day come back home.[1]
Thanos was proven right when Gamora and the Ravagers gang she's been running with came to Titan intending to hand over both their captain Lord Starkill and his nemesis Corporal Carol Danvers to justice. Nebula welcomed their ship as they landed only for Gamora to punch her in the face. Their brawl was stopped by the arrival of their father, who offered took the captives to the Court of Galactic Justice. Thanos found the lives of two criminals incapable of redemption worth nothing to hand over in exchange until Rockette revealed the Reality Stone taken from Starkill. Seeing what he did not truly believe existed until now, Thanos ordered every pirate seized and announced his intention to use the Stone to rid of the galaxy of all who pirate and pillage like they do. Upon hearing that, the pirates attacked Thanos' forces, with Nebula shielding her father from attacks. Gamora attacked Thanos from behind to take the Reality Stone from him and after checking on him Nebula lamented on how his wish to see Gamora home had turned out. Seeing how pirates like her would never change, Nebula grabbed the Stone and prepared to use it herself, but was ambushed by Zeta Flight and let go of it. Nebula was enraged and ordered the guards after the intruders, but Thanos held no ill will towars hGamora and told Nebula to let her sister go, confdent that justice would find her and her friends regardless.[1]