Scarlett Johansson’s ‘Black Widow’ has finally ushered in Phase 4 of the Marvel Cinematic Universe. The film that released on Friday, had a smashing box office opening. While trade gurus note down the numbers, it is the beautiful and tragic backstory of the Avenger and the bond she shared with her ‘sister’ Yelena Belova that has fans balling their eyes out. From Natasha Romanoff and Yelena to Loki and Thor, Wanda Maximoff and Pietro Maximoff, here’s a list of Marvel’s extremely powerful sibling duos. ‘Black Widow’ has not yet come to India, but the Twitter reactions and spoilers have given us enough to imagine the action, love, laughter and heartbreak that awaits us. The film that serves as an origins story for Natasha Romanoff, the famed Russian assassin turned Avenger, gives us an insight into her life on the run from the red room and also the story of her adopted ‘family’ of fellow spies. One thing that stands out in the film, is the beautiful relationship Natasha shares with Yelena Belova, who by the end of the film, sets out to hold those accountable for her sister’s demise. Thor and Loki’s sibling rivalry and love for each other is not only one of the biggest in comic history but also in Norse mythology. While one serves as the God of Thunder, the other is the God of mischief and has the blood of frost giants pulsing through his veins. Although Loki is adopted by Odin, he has battled side by side with Thor as true brothers for the glory of Asgard and still at times been at each other’s throats. In the world of superheroes, it is hard to find a sibling duo with a bond as strong as the Maximoff siblings – Wanda and Pietro. While one goes on to become the most powerful being when she adopts the title of Scarlet Witch, the other is known for his super speed that is only second to DC’s The Flash.