Rebecca Yarros left readers on a massive cliffhanger with Onyx Storm's plot twist ending ahead of time. Yarros is notorious for introducing seemingly minor or random details only to later shock readers with their importance to the plot. This has happened time and time again throughout both Fourth Wing and Iron Flame, so it's no surprise she chose to utilize this writing device again in Onyx Storm.

Not only does Yarros use her characters to speak about or tease the prospect of marriage throughout the novel, but she also carefully plants details that hint towards Violet and Xaden's later union. Onyx Storm's ending was in no way out of left field, and in rereading the novel, it's clear Yarros sets up their marriage plotline 40 chapters before their marriage is even revealed. All of this is done through her clever mention of the Blade of Aretia in the early novel and the quick but notable description of the many "fingernail-sized" jewels that adorn its hilt.

Rebecca Yarros Set Up Onyx Storm's Ending Twist With The Blade Of Aretia, 40 Chapters Earlier

The Blade's Introduction Feels Quite Random At First

The Blade of Aretia is first introduced to Onyx Storm's story on the isle of Deverelli when Halden attempts to barter a deal with King Courtlyn. However, Courtlyn blatantly refuses the blade as an offering, stating that it was not Halden's to give. From here on, readers become aware that the blade holds significant importance to Aretia and Tyrrendor, and was given to Navarre during the Unification 600 years ago. It's also made clear that Halden chose this specific gift knowing it might provoke certain emotions from Xaden, which felt random when never heard of the blade before.

"It's mine," Xaden says, and it takes everything I have to keep my features schooled. "Or rather, it should have been. It's the Blade of Aretia, appropriated for the royal vault by Reginald during the Unification."

— Onyx Storm, Chapter Twenty-Six

However, Yarros obviously wanted to draw significance to the blade and its importance to both Xaden and Aretia early on in the novel, and its introduction was mainly to set up their marriage at the end of Onyx Storm. Knowing this blade supplies the emerald that will sit in Violet's engagement ring, it fits that it would hold sentimental value for Xaden as well. By gifting Violet with an important artifact of Aretia, it not only signifies the love and trust he has in her, but it also helps to set Violet up as Aretia's new Duchess by adorning her with a valued heirloom.

The Blade Of Aretia's Missing Stone Gave Away Xaden's Marriage Plan

Violet Notices The Missing Stone In Chapter 47

When Violet returns to Aretia in Chapter 47 of Onyx Storm, she notices the blade they retrieved in Deverelli is missing an emerald stone on its hilt. However, she doesn't think this to be all that surprising, instead believing the blade has held up pretty well after being in Navarre's possession for over 600 years. In hindsight, readers understand that the blade didn't just lose a stone due to old age, but the emerald was removed by Xaden to create Violet's engagement ring. This was the biggest and most obvious clue Yarros set up ahead of Violet and Xaden's marriage.

When Violet first sees the Blade of Aretia, she describes the emerald stones on its hilt as being roughly the size of her fingernails — also a common stone size for an engagement ring.

However, it wasn't an easy one to spot upon the first read. The Blade of Aretia entered the narrative during a rather high-stakes moment and was never again referenced until Violet found the missing stone. However, it should have been the biggest indicator of Xaden's marriage plans, as Onyx Storm had foreshadowed and spoken of marriage throughout its entirety. It's also made clear that Xaden's marriage plan wasn't a last-minute decision after he became an asim but something he planned very early on, especially when realizing the stone was found to be missing nearly 20 chapters before Onyx Storm's end.

How Else Onyx Storm Foreshadowed Violet & Xaden's Marriage Before Its Ending

Marriage Is Mentioned Many Times Throughout The Narrative

Pretty early on into Onyx Storm's start, Xaden and many other characters make references to marriage or allude to the direction his and Violet's relationship seems to be heading. Yarros obviously used these moments to foreshadow the big reveal at the end of the novel, and in rereading Onyx Storm, there are even more clues to be caught than on the first read. At first, Yarros teases their marriage through simple comments from Xaden, making it clear that he's thought seriously about a future with Violet, but the frequency at which it's mentioned increases throughout the novel.

Xaden later refers to his and Violet's relationship as much more than typical, stating that boyfriend is "far too casual a term for what [they] are". Marriage is also discussed at length when the quest squad is visiting the isle of Hedotis, in which the leaders are urging Xaden to reconsider a marriage alliance. However, Xaden purposefully misunderstands their intentions, asking for papers to be drawn up for him and Violet instead—requesting a contract for a lifetime. Aside from the blade itself being a major clue, Onyx Storm has several one-liners that hint at his and Violet's marriage at the end.