Tagatha is the romantic pairing of Tedros of Camelot and Agatha of the Woods Beyond. Throughout the books they struggle to achieve their happily ever after and had attained a 'love and hate' type of relationship. In Book 1, they despised each other, then slowly started falling for each other. Book 2, they missed each other terribly, then noticing how the other changed, turned against each other, but at the end they chose each other. Book 3 really defined their relationship and they got to know each other more than ever, Book 4, they had a lot of moments but their relationship was fractured in the ending.
At the Welcoming Ceremony, Tedros is surprised to see fair and beautiful Sophie in Never rags and witch-faced Agatha in a pink dress. He drops his rose in shock and it fell into Agatha's hand, symbolizing their future relationship. Pretty quickly, the two take a disliking towards each other, especially since Sophie wants to stay and be with Tedros, sending Agatha home, which was a plan Agatha wasn't terribly fond of and which she blamed Tedros for. Tedros also didn't believe Agatha belonged in the School for Good, causing him to taunt her often.
After "solving" the Schoolmaster's riddle, Agatha grudgingly helps Sophie win Tedros' heart, but the plan goes wrong multiple times in challenges where Tedros felt a strong connection to Agatha's hobgoblin and coffin, causing arguments between Sophie and her. After the Trial by Tale, Tedros breaks anything he had with Sophie after he caught her using Agatha to make him fall in love with her. He takes a new interest in Agatha, as he finds out it was her words he heard in Sophie and her who he'd been drawn to this whole time.
Meanwhile, Sophie plots revenge, attacking the schools and claiming it to be Tedros' fault for breaking up with her, showing her true inner evil. Agatha tries to get Sophie and Tedros back together to keep the schools safe, but neither one wants to be with each other now. Agatha slowly falls in love with Tedros as he loves her, creating an ever after that made Sophie jealous and turn paranoid. After saving Sophie from the Schoolmaster's trap, Agatha wishes to go home with Sophie, leaving Tedros alone and heartbroken.
Throughout the first few chapters, Agatha is seen to be missing Tedros, often dreaming about him. At Honora and Stefan's wedding, upon watching the ever after she gave up, her wish for him becomes true, and Tedros senses it, and the Gavaldon borders broke, sending arrows after Sophie. Agatha and Sophie decide to go back to the Schools to get away from the attacks and find out what's going on. When they get there, they find out what their ending did: a huge war between boys and girls and Tedros was in the middle of it all, bitter in losing his princess to a girl.
Even so, Agatha still wants to see him, and with the help of her friends, sneaks into the School for Boys to see him, unaware Sophie was following her. Tedros is surprised, hurt, and happy to see her. Agatha wants to seal their ending but Tedros refuses to do it until Sophie dies, and the latter shoots a spell at the two of them, each one thinking the other tried to hurt them. Agatha runs away, back to the girls' school, to find Sophie fast asleep. She confides in Sophie in what happened and Sophie plays innocent.
After that, a bounty on Agatha's head is added to the flyers, and Agatha wants nothing to do with Tedros anymore, truly believing her happily ever after is with Sophie. However, when Sophie converts to Filip, her boy version on a mission, and gets closer to Tedros, she/he understands her enemy's point of view. They get closer and closer and in the Trial by Tale, Tedros kisses her, caught in the action by Agatha.
Agatha turns on Filip, realizing she had been tricked this whole time. Filip converts back to Sophie, and Tedros also feels tricked too. The two Evers realize how happy they could've been and decide to choose each other and send Sophie home. But as Sophie desperately attempts to stop them once more, the Schoolmaster comes and Sophie chooses him this time. He stabs Tedros, stealing his sword, and the two Evers get sent back to Gavaldon.
In the beginning, they are shown to be quarreling regularly, acting like a typical married couple. However, they both miss Sophie and eventually decide to go back for her. But not before The Elders catch them and sentence the both to death, as Agatha's punishment for letting Sophie escape, and bringing a prince back with her. Callis sacrifices herself for them, though, unleashing her magic and giving the two directions to take refuge in the League of Thirteen.
Along the way, they get attacked by zombies of defeated villains, saved by Uma. On the way, Tedros tries to reason with Agatha why he should save Sophie, saying he could make her feel loved in a way Agatha couldn't, and as he talks about her, his face turns dreamy, making Agatha jealous and annoyed. She storms off and talks to Uma about her unsureness of her and Tedros' relationship, hearing how bad Uma's ever after ended up.
After fighting more villains, and Uma getting stunned by a spell, they carry her to the League headquarters, led by a rabbit, also continuing their previous argument. After finding the League, and making some immediate enemies, their relationship gets more strained as Tedros finds out what Agatha and Uma were talking about. Merlin turns them into the opposite gender, and Dot renames them to Edgar and Essa. The coven keep them in Room 66 while they're in class, and the two of them have a moment, talking about their deepest fears and why they love each other. The moment is cut short by an annoyed Hester, and they practice their missions, Essa now the one chosen to save Sophie.
While Agatha/Edgar faces Rafal in getting Excalibur back, Tedros/Essa finds out what Sophie wants in order to destroy her ring - Tedros. She asks for one more chance, and she'll destroy the ring even if she isn't chosen in the end. At first, Agatha is furious until she realizes that Tedros is just playing along and would choose Agatha in the end anyways. But after taking Sophie back (with Hort, who followed), Agatha finds out that Sophie changed her mind and she would only destroy Rafal's ring if she is the chosen one. She also explains that Agatha wasn't meant to be a queen, while she always knew she was, reopening Agatha's doubts for the whole book. Agatha knows Good's life is on the line, so she pushes Tedros towards Sophie, knowing she was giving him up forever if she did this.
Tedros, upset with having to take refuge in Lancelot and Guinevere's house, camps out in the forest on his own, and Sophie and Agatha have time to revisit their friendship. But Tedros comes back, and takes Sophie to a sapphire cave and questions why she wants to be his queen. She tells him how she always knew her destiny was meant to be greater than any girl in Gavaldon's, but leaves out the crucial part about because she loved him, angering him. He orders her to destroy the ring, leaving her and running away to Agatha, where they make up. Sophie, outraged, wishes for Evil and Rafal rescues her, taking her back to the school.
Their relationship continues healthily as they make new plans with The League to destroy the ring and in the final battle, Agatha manages to convince Sophie. At the ending, Agatha and Tedros are last seen riding to Camelot, their ever after seemingly sealed.
They're mentioned from time to time, especially by Sophie, who is seen making absurd remarks and being unable to handle the topic of them.
At the beginning of the book, it is said that Tedros is staying away from Agatha to keep her from being worried about him and to avoid the topic of the coronation. This depresses her until he comes to her room one night and cries in her arms, but before they can speak, Lady Gremlaine finds them, and he leaves. The very next day, Merlin hosts "Couple's Therapy" in The Celestium, but mostly talks about why Excalibur couldn't be pulled out. After Agatha starts crying when Sophie is brought up, Merlin leaves and the two of them talk about the past few months, and Agatha decides on visiting Sophie. Tedros argues to no avail.
Later on, when Rhian saves them all in the Lion's mask, everyone, including Agatha, believes it was Tedros who had come to save them all. But he only comes after, with Lancelot and Gremlaine dead. Soon Tedros only confides in Rhian, and he leaves when Agatha says he can confide in her too. The two go on a double-date with Sophie and Rhian at Sherwood Forest and after they leave, the two seem to be on good terms when Tedros holds Agatha and they kiss only to be interrupted when Rhian gets them lost.
But as the story goes, Agatha begins to lose trust in Tedros and doubt whether he really is meant to be king. She tells Sophie this only to have Tedros overhear. Agatha feels guilty when Tedros confronts her but he tells her that she's right about everything, and it turns out he was doubting himself too. But soon, The Snake attacks and Tedros fights it, demanding to be the one to kill it. But Agatha is worried that he'll be killed, pulls him back, and orders Rhian to kill it. After it's done, Tedros tells Agatha that she always holds him back and the only trick is her. She gets upset and stays back, and Guinevere tells her that this was what being a queen always felt like: let her king fight for his kingdom or save him when he's in danger.
At the ending, their relationship is more fractured than the before and separated, as Rhian betrays everyone, becomes king, and imprisons Tedros.
- Friends with Sophie and have both kissed her once.
- They are both Evers