Short answers, pulled from the story.
Actress Karen Gillan portrays the character Nebula in the Marvel Cinematic Universe. She shaved her head and spent hours in makeup to become the bald, blue-skinned warrior. Her performance brought a human element to a character who was originally designed to be a cold, unfeeling machine.
The character Nebula first appeared in the year 2014 on the bridge of a ship. She was introduced as a blue-skinned warrior with a single eye and a body half-replaced by metal. This appearance marked the beginning of her evolution from a one-dimensional villain into one of the most complex figures in the Marvel Cinematic Universe.
Thanos replaced parts of Nebula's body with cybernetics every time she lost a fight against her sister Gamora. This cycle of violence and replacement was designed to make her stronger and more efficient. The process created a deep-seated jealousy and bitterness within Nebula, driving her to seek validation through combat.
In the year 2023, Nebula traveled back in time to an alternate 2014 to retrieve the Power Stone. She had to kill her alternate self to save the timeline and her sister. This moment was a turning point in her character arc, as she finally embraced her role as a hero and began to connect with others on a deeper level.
After the events of Avengers: Endgame, Nebula took on a new role as the leader of Knowhere. She worked alongside Groot to rebuild the floating head of a dead Celestial into a sanctuary for the children who had been rescued from the High Evolutionary. Her leadership was marked by her practicality and her willingness to take on the responsibilities of a mother figure.