Fourth Wing by Rebecca Yarros

Violet Sorrengail approaches her mother’s office on Conscription Day, the day when all 20-year-olds across Navarre must choose their military branch. Although Violet’s late father had trained her for the Scribe Quadrant (working with books), her mother, General Sorrengail, orders her to enter the Rider Quadrant. There, Violet will spend the next three years fighting for her life, preparing to become a dragon rider. Inside the office, Violet finds her sister Mira, a seasoned dragon rider, arguing with their mother. Mira is concerned about Violet’s prospects, given that an illness during Violet's infancy left her frail and small. But General Sorrengail stands firm in her decision, even when Mira brings up the tragic death of their brother Brennan, who died in battle as a dragon rider.

Mira helps Violet prepare for Basgaith War College, offering her a corset lined with dragon scales for protection. She also advises Violet to seek out Dain Aetos, their childhood friend, and warns her to avoid anyone with a rebel tattoo, especially Xaden Riorson. Children of rebels are forced into the Rider Quadrant as a form of punishment for their parents’ role in a failed rebellion.

To enter the war college, all cadets must cross the parapet, a narrow wall separating the rider school from the rest of the college. There, Violet meets Xaden Riorson, the son of the rebellion’s leader and a high-ranking third-year cadet. Though they feel an instant attraction, they loathe each other because Xaden’s father killed Brennan, a crime for which Violet’s mother executed him. As Violet crosses the parapet, a fellow cadet named Jack attempts to kill her—reflecting the cutthroat competition at the college—but Violet escapes. She is found by Dain, who urges her to join the Scribe Quadrant, but he ultimately accepts her and her new friend, Rhiannon, into his squad. However, the squad is soon transferred to the Fourth Wing, directly under Xaden’s command.

Training begins the next day. Dain privately warns Violet that Xaden wants to kill her and reveals that his connection to his dragon allows him to access others' memories by touching their temples. Although Violet excels in her studies, she becomes a target during sparring sessions, where other cadets attempt to kill her because of her physical weakness and her mother’s reputation. To survive, Violet strikes a deal with Rhiannon: she’ll teach her history in exchange for sparring lessons.

During initial training, cadets are allowed to challenge each other, and some of these challenges turn deadly. Violet uses her late brother’s journal (given to her by her sister) to learn her challengers’ identities and poisons them to give herself an advantage. One night, while collecting ingredients for poison, she overhears a secret meeting of rebel children, lead by Xaden. Afterward, Xaden approaches her, swearing her to secrecy in exchange for a future favor.

Cadets are then tasked with climbing the Gauntlet, a vertical obstacle course meant to simulate the challenges of riding a dragon. Violet bends the rules during her climb, frustrating a wingleader. Her squad is then presented to the dragons, but several cadets are incinerated for being rude or impertinent. Among the dragons is a small golden feathertail, a rare breed known for its reluctance to bond with humans.

When the Threshing event arrives, cadets are released into a valley to bond with dragons. Because dragons are scarce, many cadets resort to killing others to improve their chances. Violet hides from Jack and his cohorts but realizes they intend to kill the golden dragon, Andarna (who has started talking to Violet). She defends the dragon, sustaining serious injuries before Xaden and his dragon, Sgaeyl, arrive. Violet fights off Jack and a second cadet, but a rare black dragon, Tairn, arrives and kills the third cadet (and communicates with Violet), they then take Violet back to the college. Both Tairn and Andarna bond with Violet, making her the first rider in history to have two bonded dragons.

Violet’s physical strength improves, but she struggles during flying practice (she can't stay in her seat). One evening, Tairn wakes her as six unbonded cadets attempt to kill her. Andarna uses her time-stopping ability to freeze the attackers until Xaden can intervene. Violet accuses a senior cadet of orchestrating the attack, and the cadet is executed after being found guilty.

Xaden and Violet meet with their dragons and discover that Andarna is not a rare breed but a child dragon, whose ability to stop time must remain a secret until she matures. Meanwhile, Xaden asks Liam, another child of a rebel, to act as Violet’s bodyguard. During a moment of passion fueled by their dragons, Xaden and Violet share a kiss. Violet later fights Jack, exposing him to an allergen to save herself. During the annual Squad Battle, Violet’s squad steals a map of military outposts from General Sorrengail, winning the chance to shadow soldiers on the front lines. While there, Violet reconnects with Mira, but the visit is cut short when gryphon fliers from the enemy country of Poromeil attack. Mira makes Xaden take Violet back to safety.

During a capture-the-flag game, Violet saves Liam from Jack’s attempt on his life. In doing so, she manifests her unique “signet”—the ability to control lightning, which she uses to kill Jack. This is Violets first kill, and it makes her sick. At some point Xaden comes to talk her through her feelings.

Reunification Day arrives, commemorating the defeat of the separatists and the rebellion. It also marks the anniversary of Brennan’s death, and Violet seeks out Xaden, who is mourning his own father’s loss. The two finially confess their feelings and spend the night together. Their night in interuptted when the War Games begin, and Xaden leads a group of rebel children, and Violet, to an outpost outside the empire (Violet doesn't recognize that she is the only non rebel child until later). There, they meet gryphon fliers, and Xaden confesses that he has been secretly supplying them with weapons to fight the venin (Violets dragons also knew about this)—evil creatures that steal magic from the earth. Violet is heartbroken by his betrayal but learns that their mission to help the fliers is actually a trap set by the college to kill them.

Despite the option to flee, the group decides to stay and fight. During the battle, Liam dies when his dragon perishes, and Violet is stabbed with a poisoned knife. She uses her lightning abilities to ensure their victory. Afterward, the survivors take her to an abandoned fortress to heal. When she wakes up after three days, Xaden swears his loyalty to her and vows to help her trust him again, though Violet remains wary of his intentions. Finally, Violet’s brother Brennan—whom she believed was dead—arrives and welcomes her to the revolution.

Thanks Super Summary for helping me remember what else happened. 

https://www.supersummary.com/fourth-wing/summary/?searchId=28f8dc5b-640c-4f76-b00b-1361147d374b&searchPosition=1