Despite being siblings, certain characters in this Marvel tale must face off against their own kin.
Marvel superheroes come from diverse family backgrounds. One character hails from a family with a tradition of protecting Earth and fighting against evil. However, there are also characters who must stand against their own relatives when their siblings turn out to be antagonists.
Here are 5 instances of 'fraternal turmoil' in Marvel films, each battle leaving many in sorrow and contemplation.
Gamora and Nebula

Gamora and Nebula, not biologically related siblings, are both adopted children of Thanos. Despite that, they grow up as sisters in the same household, both trained to be professional assassins. This dynamic often leads to discord between Gamora and Nebula.
While growing up and training together, Thanos often engaged in battles with Gamora and Nebula for the purpose of honing their skills. Consequently, both constantly competed to prove who was Thanos' most skilled offspring. However, one day Gamora realized that she was merely a 'tool' for Thanos and decided to leave her father to join the Guardians of the Galaxy.
At this point, Nebula remained loyal to Thanos, persistently hunting Gamora to intensify their rivalry. After numerous events, Nebula eventually awakened to the truth, just like Gamora, and distanced herself from Thanos. In recent Marvel films, we've witnessed their growing bond, despite still engaging in fierce arguments.
Thor, Hela, and Loki

Being a superhero, Thor has infamous siblings who are well-known villains in the Marvel universe. Loki, his adopted brother, known as the 'God of Mischief,' was even a villain in two Marvel films, Thor (2011) and Avengers (2012). Subsequently, Hela, Thor's sister, dubbed the 'Goddess of Death,' emerged as a major antagonist. Previously imprisoned by her own father for her overpowering lust for dominance, Hela was willing to destroy anything in her path. Thor had to confront Hela in Thor: Ragnarok (2017) to prevent the universe's destruction.
As a result, Thor continually faces challenges from his siblings in his solo films. However, Thor and Loki's relationship can be described as a love-hate dynamic, as they sometimes collaborate for certain benefits. Meanwhile, Thor's relationship with Hela resembles that of a superhero and a villain, as the God of Thunder is forced to eliminate his sister to prevent the universe's annihilation.
Shang-Chi and Xialing

During their childhood, the sibling bond between Shang-Chi and Xialing was harmonious. However, everything changed when their mother passed away, and Wenwu, their second father, sent Shang-Chi away to seek vengeance for her death. Shang-Chi never returned, leaving Xialing behind as a young child with a criminal father.
Shang-Chi and Xialing only reunited when both had grown up. Their first encounter after many years unfolded in a battle on a battlefield. As an older brother, Shang-Chi exercised restraint in not hurting his younger sister, but Xialing, harboring resentment for the brother who abandoned her, did not share the same sentiment.
However, after resolving misunderstandings, both truly reconciled to defend their homeland against their father and creatures from other realms. Yet, at the end of the film, they took divergent paths. Shang-Chi joined the Avengers, while Xialing assumed leadership of her own criminal organization.
Black Bolt and Maximus

This sibling pair actually originates from the Marvel comic series titled Inhumans. In the comics, Black Bolt is the leader of the Inhuman Royal Family, highly intelligent, and remarkably merciful. He has a younger brother named Maximus, who is slated to succeed him as the leader of the Inhuman Royal Family upon his demise.
However, Maximus harbors a longstanding desire to become the leader of the Inhumans and genuinely dislikes the hierarchical system within his family. This eventually leads Maximus to betray his brother multiple times and attempt to remove Black Bolt from the throne. Even when his plans fail, Maximus often exploits his brother's forgiving nature to escape punishment.
Meanwhile, Black Bolt almost always believed that Maximus would change at some point, even entrusting him with various tasks. However, in reality, Maximus knows no bounds, always having his own agendas and a relentless desire to eliminate his brother to seize power.
Eros and Thanos

In the film Eternals (2021), we finally witness the live-action portrayal of Eros, also known as Starfox. In the comic version, this character is the brother of Thanos, who became a central antagonist in the MCU's Infinity Saga. While the films haven't depicted the animosity between Eros and Thanos, they frequently clash in the comic version.
In the comics, their enmity arises from Thanos' actions, who decimated the population of their home planet, Titan. Ironically, Thanos' actions also resulted in the death of their parents. This fuels Eros' hatred towards Thanos, vowing to avenge the death of their parents.
In the MCU, Thanos met his demise in Avengers: Endgame (2019). However, upcoming MCU projects might provide flashbacks showcasing the past of Eros and Thanos after the death of their parents. Through these scenes, we might finally witness the deep-seated animosity between these siblings.