I know I already know so much about her, BUT how does Cassidy get along with each of the original six avengers if she meets them?
So Cassidy does meet the original six Avengers when she ignores Professor Xavier’s directive for his staff to not get involved in the Battle of New York. The risk of exposure was far too high with the news reporting on events, but Cassidy sees her brother on the TV and bolts. She obviously gets along great with her older brother, Clint. He took her in after he found her in foster care after their parents died, became her legal guardian. Because of their significant age gap (15 years) he’s more like a father than a brother, which can be a bit of a problem from time to time. When they fight, they alternate between screaming and signing. They also sign when they wanted to have a private conversation in public, especially when they want to talk shit about people right in front of them. Clint knows she’s a mutant and keeps her secret from SHIELD and the rest of the Avengers, the only person outside of Xavier’s who knows her secret is Laura and, eventually, their kids. As she opts to wear a mask to disguise herself during the Battle of New York, he doesn’t even tell them that the mysterious, masked, superpowered woman helping them is his sister and he helps cover her escape afterwards.
She and Bruce get along fairly well, given that they’re both academics albeit in different fields. When they’re formerly introduced and the truth about mutants is revealed, Bruce initially wants a sample of her blood to see if he can unlock the secret of the mutant gene. Obviously, she declines this offer but makes him an offer of her own in return. Cassidy invites him to the school to meet her former professor turned colleague, Hank McCoy. He’s the smartest man in the world, that she knows of; if anyone could help him with his Hulk problem, she figures he might be his best bet. Bruce is stunned by the offer, considering how he’d offended her, but graciously accepts and begins a solid friendship with Hank and most of the staff at the school. He later tells her that, had he been around during the Sokovia Accords, he would’ve sided with Cap. Considering he’d been on the run from the government for years, he understood all too well the fear of being under their thumb to be used at their command. They respect each other a great deal.
Thor is like, her best bro. They get into little competitions over whose stronger: “I can command lightning.”/“I can destroy solid objects when I scream.”/“I can fly!”/“So can I!”/“Only when you scream!”/“And you can only do it while holding that hammer!” Like, they’re such children about it. Thor loves to regale her with stories from his adventures on Asgard, which she loves because holy shit there’s a whole universe of sentient alien life, and she tells him stories from her favorite books, which he enjoys because he’s so fond of Midgard. Thor is genuinely curious about mutants and finds similarities in some of the mutations she tells him about with other beings he’s met across the Nine Realms. Cassidy actually teaches Thor a few signs, after he took an interest during one of her and Clint’s conversations. He’s pretty bad at it, but she gives him points for trying.
Cap is someone she respects but finds, like the Professor, has an almost naive ideology of the world. He wants to see the best in people, believe that people are inherently good and decent but she knows all too well that that’s just not true. Unlike the X-Men’s primary nemesis, Magneto, Cassidy doesn’t believe that humans are inferior and should be wiped out; she wholeheartedly believes in the Professor’s dream that, some day, humans and mutants will coexist. It’s just hard to see that day happening in her lifetime. Cap sympathizes with the plight of mutants, considering he’s an enhanced human himself. Although he felt odd visiting the school at first, he began to see it almost like home since he could basically be anonymous there. It also reunited him with Logan, who he’d met back in WWII although Logan has no memory of him. Cassidy often trains with Cap, finding him to be one of the best people to keep her skills sharp. She also helps catch him up some of the things he missed while in the ice.
The only ones Cassidy doesn’t get along with are Tony and Natasha. Cassidy generally doesn’t like Tony’s snarky and dismissive attitude. But he’s also self-proclaimed reformed war profiteer and she doesn’t trust him. She believes, for the right price, he’d harm mutants. Be it experimentation or locking them up or a registry, she simply doesn't trust him and this is a very founded fear as we discover with the Sokovia Accords. She’s very protect of her students and the rights of mutants all over the world to maintain their freedom and autonomy, something Tony is a direct threat to. Natasha, on the other hand, she doesn’t trust because of how she and Clint met. Since the MCU never went into it, I’m going with the comics origin wherein Natasha is still a Red Room operative who manipulates and uses Clint to her own ends and nearly gets him killed in the process. Regardless of Clint and Laura’s trust in Natasha, Cassidy still has very bitter feelings towards her and is wary.
