siblings
who is sisters in Guardians of the Galaxy a.k.a daughters of Thanos
Gamora and Nebula
who is siblings in Black Panther
T'challa and Shuri.
who is thor's siblings
Loki and Hela
who are twins in Avengers: Age of Ultron
Wanda and Pietro Maximoff
who is siblings in Guardians of the Galaxy holiday special
Mantis and Peter Quill