Kitheo

Kitheo is the het ship between Theodore 'Theo' Decker and Katherine 'Kitsey' Barbour from the The Goldfinch fandom.

The Goldfinch (2013)
Kitsey was Andy's, Theo's best friend, little sister and the family's only daughter. She and Theo first know each other when Theo arrives in the Barbour's house being temporarily adopted by them because of his mother's death. Kitsey heavily disliked Theo for usurping attention from her parents, and either ignored him pretending to not know Theo or made snarky remarks at him when they were in the house.

"There were a lot of tantrums and pouting, a lot of eye rolling and hostile giggling on Kitsey’s part, as well as a baffling (to me) upset—never fully resolved— where she complained to her friends and the housekeepers and anyone who would listen that I’d been going in her room and messing around with the piggy-bank collection on the shelf above her desk."

It's later revealed that Kitsey had her guard up because of Platt, who told her Theo would steal things from her room if she didn't keep the door locked. After a year of them living in the same house, Theo says Kitsey has started being nicer to him, as if someone had drawn her aside, when he was thinking about the possibility of the Barbour family adopting him.

They reunite 8 years later when Theo accidentally finds Platt, and gets into touch with the entire Barbour family again. She quickly shows interest on him, a complete contrast to their old dynamic.

"Kitsey and I hadn’t talked much—we hadn’t been able to, thanks to Mrs. Barbour; but almost every time I’d glanced in her direction I’d been aware of her eyes on me."

There's a time jump in a scenario where they're engaged and Theo's gifting her emerald rings that belonged to his mother. While she appreciates the gift, she says that emeralds aren't her stone, but will wear them anyways for his sake. Theo explains that after meeting the Barbour family again and having dinner with them, Kitsey and him would see each other every day practically.

In these months spent together, Kitsey is the first one to bring the topic of marriage and asked Theo about it, saying that Mrs. Barbour would be pleased. Theo remarks that he would never forget Kitsey's smile when they were telling her mom about the engagement, in disbelief that he could make Kitsey so happy and be happy like that himself. In the four months that passed, he could only ever think of Kitsey and how lucky he was. Still, he could not shake his feeling of sickness off for unknown reasons. He reveals he was never gonna be over his obsession with Pippa, but he had to deal with it. Instead, he gets slightly obsessed with Kitsey to compensate his feelings:

"All summer long I had been practically delirious: tingling, daffy, energized, running on gin and shrimp cocktail and the invigorating whock of tennis balls. And all I could think was Kitsey, Kitsey, Kitsey!"

Still, it wasn't all perfect. What specifically bothered him with Kitsey was the arrangements of the marriage with the honeymoon plans and rising to an uncomfortable social pace. Even with all the negative feelings, Theo says he was never so sure of the future: everything felt right, especially because of Mrs. Barbour happiness and the light of their interactions.

When coming back to the memory of when they were kids, instead of annoyance Theo remarks feeling erotic delight from the interplay of their relationship between before and after.

"“Oh, [Kitsey]'s amazing,” I’d said venomously. “I’ve been in love with her ever since we were kids.” Which—in all sorts of ways I was still coming to realize—was absolutely true. The interplay of past and present was wildly erotic: I drew endless delight from the memory of nine-year-old Kitsey’s contempt for geeky thirteen-year-old me (rolling her eyes, pouting when she had to sit by me at dinner). And I relished even more the undisguised shock of people who’d known us as children: You? and Kitsey Barbour? Really? Her? I loved the fun and wickedness of it, the sheer improbability: slipping into her room after her mother was asleep—same room she’d kept shut against me when we were kids, same pink toile wallpaper, unchanged since the days of Andy, hand-lettered signs, KEEP OUT, DO NOT DISTURB—me backing her in, Kitsey locking the door behind us, putting her finger to my mouth, tracing it across my lips, that first, delicious tumble to her bed, Mommy’s sleeping, ssh!"

Theo, however, reflected that Kitsey was simply too perfect: she was never tired, never unhappy, nothing ever moved her at all. What bothered him the most was the fact that she didn't seem haunted over the death of her older brother and father at all. He seems to be projecting on her because of the fact he has never moved on from the death of his mother, so now he's questioning Kitsey's grief.

However, what also gradually starts bothering him about Kitsey is some of her habits when disappearing and just the aspect that she's hiding something from him. While he's in the street, he catches her kissing Tom Cable, and for the first time ever, Theo sees her crying. Even with her sadness, it was clear they had joy in being with each other. It becomes clear to Theo that she had been cheating on him and her entire family knew of it.

Theo brings it up and they have a heated and enraged conversation about the cheating. At first, Kitsey denies, but then admits that she thought that it wouldn't matter until they got officially married, but promises she wouldn't see Tom anymore. Still, Kitsey convinces him of still marrying her, using the argument that they're better people when they're with each other, that her mom has been way better since the engagement and that he wouldn't like to spoil any of that.

"Mommy loves you so much. So much. You saved her life coming along when you did. She talks, she eats, she takes an interest, she walks in the park, she looks forward to seeing you, you can’t imagine how she was before. You’re part of the family. (...) It’s the right thing to do. Marrying. We’re a good match. It makes sense for everyone involved, not least us. (...) Why should we let this spoil things? After all, we’re better people when we’re with each other, aren’t we? Both of us? (...) We’re a good couple. We like each other. We get along. (...) let’s both be good, and truthful, and kind to each other, and let’s be happy together and have fun always."

After the conversation, Theo finally admits he wasn't sure if he really loved Kitsey in the way he wished he did. Later on, Theo has a talk with Boris about Kitsey, where he already clocks that Theo isn't really in love with her.

And when he talks with Pippa, Theo loathes Kitsey's habits of avoiding serious topics twice.

"I felt like a different person in her company, a better one, could say things to her I couldn’t say to anyone else, certainly not Kitsey, who had a brittle way of deflating serious comments by making a joke, or switching to another topic, or interrupting, or sometimes just pretending not to hear. (...) Kitsey—who was always at least partly somewhere else, who loathed serious talk, who at a similar turn would be looking around for the waitress or making whatever light and/or comic remark she could think of to keep the moment from getting too intense."

In their engagement party, Theo notices Kitsey's relief in him showing up since she wasn't sure he'd be there. As she promised, she wore the emerald earrings he gave her. He talks about Tom with Platt, and he says that Theo was the best thing that ever happened to Kitsey, since Tom wasn't good to her at all. Theo has a thought that Kitsey was sleeping with the person she really loved while marrying a person that would please her mother the most and that was a smart move. Boris shows up and tells Theo they need to leave to get The Goldfinch back. He obeys, and goes to tell Kitsey he needs to leave. They engage in some public display of affection for the photographers take pictures of the "happy couple" together before Theo has to leave. Because of her understanding of the situation, Theo thinks that "You had to hand it to her: she was as cool as dammit."

When Theo is planning suicide in Amsterdam, he writes a letter to Kitsey letting her know that the reason for killing himself is not the fact she cheated on him.

"Dear Kitsey, I’m terribly sorry about this but I want you to know that it has nothing to do with you, and nothing to do with any of your family. Your mother will be receiving a separate letter which will have a bit more information but in the meantime I want to assure you, privately, that my course of action has not been influenced by anything that has happened between us, especially events of late."

In the ending, Theo barely mentions Kitsey, only in his discourse about how we couldn't change our hearts and reflected on what we could do about it, using her as an example of someone who tries to repress what her heart truly wants.

Overall, Theo's cling to Kitsey is definitely not because of true love from either sides. In his side, it's both an attempt to conform in a heteronormative society, and an attempt to reconnect with his mother figure through making Mrs. Barbour happy with the marriage. Even with Kitsey he attempts to "mother-fy" her with the emerald earrings just to try to love her, in an extreme similar way he does with Pippa. In Kitsey's side, it's an attempt to get away from Tom Cable and supress her own heart, since her entire family hates him and Tom just doesn't truly love her. It's also just trying to make her family proud to marry the "right" person, especially because of Andy and her own depression. While they clearly don't love each other romantically, they respect each other and have reasoning to be together, even if they're technically unhealthy.

The Goldfinch (2019 film)
In the movie, Kitsey's distaste to Theo is only shown in her first and only scene of her as a child in the movie. Toddy asks Theo where his dad is, and when Theo replies that it's a great questions, Kitsey mockingly exclaims with a smile "oh, my god!", receiving a look from Mrs. Barbour for making fun of him.

Later, they already appear married and it goes the exact same way in the movie, but with dialogues slightly different. Their conversation about the cheating is more emotional than enraged, while Theo is crying from the start and not raising his voice at her.

Theo's conversation with Boris is also shorter:

Kitsey is also less understanding of Theo suddenly leaving their party, looking way more disappointed with him.

Fanon
Kitheo is the fourth most written ship on AO3. It is also the first most written ship for Kitsey and the third for Theo. Even with its canonicity and potencial, it's a ship that is easily overshadowed by Boreo, who grabs the spotlight of the entire fandom. Kitsey isn't a popular character and is really disliked in general, so most people don't bother to ship her with anyone, not even with Theo or Tom, her two canon love interests. And in the rare case she's shipped with someone, it's with Pippa or in a poly trio with Kotku added. Most of their works are aiming for a later-Boreo, not really involved in the ship Kitheo itself.

Fandom
FAN FICTION

Trivia

 * Kitsey was nine and Theo was thirteen when they first met, meaning they have a 4 year age difference.
 * Theo calls her "Kits" as a nickname, even if "Kitsey" is already a nickname.