For those who have been anxiously waiting for her arrival in theaters since the post-credit scene rolled at the end of Avengers: Infinity War, fans went into Captain Marvel with little sense of who the characters were. This was partially due to the production keeping spoilers under wraps, but also a result of not knowing how much of the comic books' origin story the film was planning to keep, and how many characters would roll into the next Avengers film. Many left asking the question: Will Jude Law be in Avengers: End Game? Warning: Spoilers for Captain Marvel follow.
When fans first meet Vers, she's a member of Starforce, a half-Kree woman with a past she cannot remember. Her commanding officer is Yon-Rogg, played by Jude Law, who has been training her up to be one of the elite fighting squad as part of the ongoing Skrull-Kree war.
Yon-Rogg has a bit of a personal vested interest in Vers' training, and he's pleased when she is selected to be part of a mission to extract an undercover Kree agent. But the assignment goes sideways when it turns out this has all been an ambush. Vers makes up on a Skrull ship, her mind attached to their device as they try to extract her memories, that may or may not be related to her abilities.
What Vers doesn't know, and the audience doesn't learn until she gets to Earth, is the Skull-Kree war isn't the fight she thinks it is, and the enemy she sees in her dreams is the wrong one.
The Skrulls aren't a deadly enemy. They're a homeless, persecuted people the Kree are massacring. When she remembers the crash that changed her life, it's a Skrull she sees coming out of the smoke who shot down her plane. However, when she listens to the black box recording, she learns it was Yon-Rogg who shot her down.
Her mentor, Mar-Vell (Annette Bening) was inventing an engine which would let the Skrulls escape their tormentors. Yon-Rogg wanted to stop Mar-vell. When he saw Carol gain her powers from the engine's explosion, he kidnapped her, experimented on her, put a device on her neck to suppress her abilities. His teachings aren't to build her up, but keep her down.
Once Vers learned her real name (Carol) and how much Yon-Rogg lied, she realizes she's been fighting with one arm tied behind her back the whole time. Ripping off the device suppressing her abilities, she finally can kick Yon-Rogg's butt up and down the dessert. The irony is, she doesn't need to beat him anymore. Even as he challenges her to prove herself his worth opponent she just photon blasts him into a rock.
She doesn't need to prove herself to anyone, not even a small man like him. She pops him back in his jet and sends him back to Kree with a message she's going to end the Kree war once and for all.
Will Yon-Rogg follow Carol when she returns to Earth in Endgame? It's not clear. If he does, it will be not as her commander or her friend, but as an enemy.