Nebula

Nebula – who was played by Karen Gillan in 2014’s brilliant Guardians of the Galaxy movie – was presented as one of Thanos’ adoptive daughters. She was, however, explicitly quoted as not being his favourite and, by the end of the movie, she had grown tired of him and was willing to side with Ronan when it came to attempting to take the Mad Titan down.

That being said, she didn’t make it known to him that she resented him, so she could quite easily attempt to take him down by feigning siding with him during the Infinity War movies, only to double-cross him by the end.

This would mirror what actually happened during the Infinity Gauntlet comic book arc, when she donned the Infinity Gauntlet itself when Thanos (her alleged grandfather in the comics) was prone and undid everything he had done – even restoring her own disfigurement in the process (perhaps she could restore the hand she lost in Guardians of the Galaxy in doing so in the MCU).