The second episode of What If...? followed the adventures of T'Challa (Chadwick Boseman) if he had been Star-Lord, and it included many minor characters from the Guardians franchise, including Carina (Ophelia Lovibond), the Collector's forgotten "assistant." In What If...?, T'Challa inspired Carina to free the Collector's prisoners after the Ravagers left, giving her the much-needed vengeance that Guardians of the Galaxy didn't. However, so did one of Lovibond's other acting roles -- Kitty Winter in the CBS procedural Elementary.
Carina first appears in Thor: The Dark World's first post-credit scene, ushering Sif (Jaimie Alexander) and Volstagg (Ray Stevenson) into the Collector's facility. Virtually nothing was known about her, including whether or not she worked for the Collector voluntarily. However, there were lingering shots of other imprisoned creatures in his warehouse and her formal, rehearsed way of speaking and moving implied that she was under strict orders. She cast a sly glance at the Reality Stone when it was exchanged, but nothing came of it.
Her first scene in Guardians of the Galaxy confirms the tragedy of her situation, though: she scrubs the glass of a prisoner's enclosure, and when the Collector speaks to her, he threatens her with the fate that had befallen his previous "assistant." Carina glances over her shoulder and sees another woman, who's clearly of her same species and dressed in a more bedraggled version of her uniform; she's kept on her knees in another enclosure with her wrists bound and a collar around her neck.
When Gamora (Zoe Saldana) and the others bring the Power Stone to the Collector, Carina once again introduces them and goes through the motions. She listens intently as the Collector explains the Infinity Stones and, when he moves to get the Guardians' payment, she goes to grab the stone. The Collector tries to dissuade her, and her caged cohort looks horrified behind her, but Carina shouts, "I will no longer be your slave!" and takes the stone. It explodes her and the Collector's warehouse, but the Collector survives. Later, his collection is ultimately restored, and Carina is forgotten, her sacrifice and suffering both for naught.
In 2014, the same year that Guardians of the Galaxy premiered, Lovibond began appearing on Elementary as Kitty, Sherlock Holmes' (Jonny Lee Miller) new protégée. Kitty had been kidnapped and raped some years prior, leading her to become fixated on helping Scotland Yard solve other violent crimes. Holmes took her under his wing to teach her to be a detective and brought her with him when he returned to New York City; Watson (Lucy Liu) also became a mentor to her during this time.
Learning to be a detective gave Kitty purpose and autonomy, and Holmes and Watson encouraged her to take the necessary steps to heal from her trauma. She was intensely protective of abused women and angry at abusive men, as could be expected. When her abuser Del Gruner (Stuart Townsend) surfaced in New York, she planned and then carried out vengeance against him. Like her counterpart in the Arthur Conan Doyle story The Adventure of the Illustrious Client, Kitty disfigured Gruner and exposed his crimes to the police. She then fleed to escape prosecution.
Kitty returned to Elementary in the fifth season and is revealed to have been working as an investigator for an organization that helps trafficked women. Prior to her reappearance, she'd decided to work instead as a counselor with the same organization because she had become a mother, and though she feared Holmes would react poorly to this, Holmes and Watson became her son's godparents. Kitty also showed up at the beginning of Season 7, helping Holmes and Watson professionally and as a friend.
Kitty got justice for herself, successfully fulfilling a fantasy that's common among abused women. Her story didn't end with revenge, though: she went on to live a happy and successful life, helping others who'd also been traumatized and growing into someone that wasn't purely defined by her own horrific past. It's the kind of ending that characters like Carina, who would rather die than continue to live under the abusive thumb of the Collector, don't even think to dream of. Still, it's also the ending that they deserve. The fact that Kitty appeared just months after Carina is probably a coincidence, but it feels almost like Kitty was a direct response to Carina and a chance to give her a better end.