Rain of Shadows and Endings by Melissa K. Roehrich

Here is a summary with spoilers for Rain of Shadows and Endings

A new world was created by the gods—the Firsts. A world where they could place their legacies without fearing those legacies would one day overpower them. The gods are as follows:◦ Falein: Goddess of wisdom and cleverness.◦ Celeste: Goddess of the sky and moon.◦ Anala: Goddess of day, fire, and the sun.◦ Serafina: Goddess of the stars and dreams.◦ Achaz: God of beginnings.◦ Arius: God of endings.

The gods chose their most promising children and placed them on this world to find their own way. They also left behind a gift: the fae, who are bound to serve the Legacies.

Enter Tessalyn Asura, a fae who has long been forgotten by her people—and she's just fine with that. All she wants is to live quietly, hidden from the Legacies, and spend time with her friends. But everything changes when her name is called to become a Source. Sources are selected every five years by the heirs of the kingdoms. This year is unique: all six kingdoms have heirs selecting a Source. The Source is bonded to their chosen heir and becomes their wellspring of power. Tessa never expected to be chosen—she was never trained for it. But when Theon, one of the heirs, names her as his Source, she has no choice.

Theon is pleased with his choice, despite his friend Luka’s warnings. He quickly discovers that Tessa is far more challenging than he anticipated. Within minutes of being claimed, she tries to escape—and gets hurt in the process. He also realizes how little she knows about the bond or what it means to be a Source. He explains that he must mark her four times and that their bond will strengthen over the course of a year as they endure trials with the other heirs. Theon gives her a drug and takes her to a priestess, where the first mark is placed.

The first mark is agonizing. All Tessa feels is pain—and a growing fury toward Theon. Worse, she begins to see Luka as the more protective one, not realizing that Theon already feels willing to do anything for her. Two painful days pass, and it only gets worse when the second mark must be placed. Tessa is in agony for days, slipping in and out of sleep, while Theon—and occasionally Luka—stay by her side.

When Tessa finally wakes, she resumes her anger toward Theon. Still, she's forced to start learning about him, his family, and what being a Source actually means. She quickly bonds with his brother Axel, who is kind and easy to talk to. But Theon’s father—who also has a Source—is a different story. At their first dinner, he treats Tessa like an object, just as he does his own Source. He tells Theon he must discipline her better, to treat her as something lesser. Then, in front of Tessa, he announces he's seeking a spouse for Theon. This hits Tessa hard. The bond is already drawing her closer to Theon, and the thought of having to share him is unbearable.

Determined to escape, Tessa seizes an opportunity—but Theon catches her by day’s end. Broken and defeated, she realizes Theon has won for now, and resolves to be the perfect Source. Theon hates this version of her—the one who doesn’t fight back—but he accepts it. The days blur together. Tessa is never alone and is usually at Theon's side. One day, while she’s with Axel and they receive unexpected visitors, Axel urges her to run. She does, but is pursued. In a desperate moment, a crevice opens beneath her, and golden figures with swords emerge. They fend off her attackers long enough for her to escape—before vanishing without a trace. Theon and Luka find her soon after, shaken and in tears.

That night, during dinner, Theon’s father reveals he knows what happened. He’s upset because Tessa’s earlier tests should have placed her under air magic, but what she did seemed more like earth magic. Tessa is confused—she insists the trials were so intense there was no way to cheat or suppress her power. Meanwhile, Theon, Axel, and Luka are getting closer to enacting their own plans, but Tessa still refuses to fully accept the bond.

Because of Tessa’s unexpected use of magic, Theon’s father and Theon decide to test her again. The trial is brutal and leaves her injured, but the results are inconclusive. However, they reveal something astonishing: Tessa is destined to become the most powerful magic user. Theon chooses not to tell her, instead hiding the results from his father. The revelation excites the three men—they just need Tessa to submit, and their plans will fall into place.

Though Tessa’s mind and body are still recovering, she’s forced to attend a dinner with Theon and his potential suitor, Felicity. Felicity is kind to her, but Tessa loathes what she’s being molded into. That night, at their hotel, she meets a mortal named Tristan. He’s warm and easy to talk to—until Theon intervenes and tells her she must stay away. Later, she sneaks out and finds Tristan again. They share an hour together, and for the first time in a while, Tessa feels like herself. But her situation worsens when Theon, Axel, and Luka begin to ignore her—especially after a magical outburst from her.

The night before they leave for the Acropolis, Theon makes a deal with Tessa. If she convinces everyone she’s accepted the bond, he’ll let her live how she wants—with as much freedom as possible. Tessa agrees, and they form an official bargain.

As they travel to the Acropolis, Tessa reads about something called a guardian mark. Many Sources are bound to these marks, which force them to sacrifice themselves for their masters. She becomes worried—until she learns Theon already has a guardian bond with Luka, which makes sense since Luka can shift into a dragon. It’s also revealed that Theon plans to overthrow his father, who is attempting a full kingdom takeover. Theon wants no part of that future.

When they arrive at the Acropolis, Tessa receives her new schedule. To her horror, she’s assigned weekly sessions with her former den mother—the one who deemed her unworthy and frequently punished her. The encounter sends Tessa spiraling. She runs to clear her head, only to be attacked by two vampires. Luckily, Luka (in dragon form) and Theon arrive and kill them. Furious, they confront Tessa. She refuses to explain why she ran, so Theon responds by increasing her restrictions. She’s forced to start self-defense classes—with Luka as her trainer. Luka, too, has reached his limit with her stubbornness. During a training session, Theon and Axel restrain her and place a new mark on her. They also mark themselves, allowing them to track her location and summon her instantly.

Soon after, Tessa is told to prepare for a ball attended by all heirs, their Sources, and other guests. She’s allowed some freedom—specifically, in who she can talk to—but must stay within Theon’s line of sight. She agrees, especially when she sees Tristan again. This time, she realizes he’s not a mortal, but a Legacy. She thanks him for his kindness and asks about the power that allowed him to disguise himself. They share a few dances, and Tristan encourages her, telling her she can endure and survive anything.

But there are immediate consequences. Tessa is now known to be friends with Tristan Blackheart—an influential and mysterious Legacy. The other kingdoms grow suspicious of her and Theon. Before Theon can act, his father arrives and brutally punishes him by killing his housekeeper. Enraged, Theon locks Tessa in a wine cellar—despite knowing it echoes the abuse she once endured. He leaves her screaming. By morning, when he returns, she’s covered in glass, and something inside her has changed. She’s docile, agreeable—willing to do whatever Theon asks. He hates it, but he has no choice. That night, her magic is to be tested again.

During the trial, a mysterious figure joins her on stage, touches her hand, and her magic erupts. She blacks out and wakes next to her mortal best friend, Dex, and the mysterious figure. They reveal she isn’t fae at all—she carries the blood of Achaz. The stranger came to awaken her magic. They return her to Theon, who tries to help as best he can, even adjusting her magical restraints to stabilize her. But in her mind, Tessa is already making plans. For the first time in her life, she has something to live for—and she intends to bring terror upon those who hurt her.

In the epilogue, two gods converse. The male says he needs someone to travel to another world—to train his daughter. The female is shocked that he wants to help her, but warns that if he’s serious, they’ll need the aid of the Queen of the World Walkers.