Fourth Wing Book 4 | Everything We Know and Everything We Dread

⚠️ Full Onyx Storm spoilers throughout. You know the drill.

When Rebecca announced she was taking a break from writing, we all collectively screamed into the void, then got to work figuring out what that 4th book might actually hold. Aside from stalking Yarros and arguing over who “the brother” there are many more things we readers think we may have figured out.

This post is for the readers who want the actual status update on Fourth Wing book 4, what we know, what Yarros has confirmed, and what the fandom is currently screaming about in lieu of a release date.

• Part 1: Onyx Storm Theories That Might Actually Be True
• Part 2: The Wildest Empyrean Theories Fans Still Can’t Let Go Of | Is Violet a Dragon?
• More Books Like Fourth Wing to Hold You Over

Takeaways

• As of early 2026, Rebecca Yarros has officially started working on book 4. Index cards are out. The playlist is brewing. A 2027 release is the most realistic target, though hopeful people are eyeing late 2026.
• The identity of the “venin brother” at the end of Onyx Storm is still unconfirmed, which means fandom has been arguing about Bodhi, Garrick, Aaric, and Brennan since January 2025.
• The W‑pattern theory for the series’ emotional arc predicts book 4 will be the absolute low point before book 5 rights everything. If that’s true, pack accordingly.

When is the Fourth Wing book 4 release date?

No official date yet but here’s what we actually know.

On January 23, 2026, Yarros posted on Instagram that she was close to starting book 4, and by mid‑March 2026 she confirmed she was in it: index cards out, playlist brewing, the words “Navarre is still… for now 😉” attached. 

Based on the release pattern (Iron Flame November 2023, Onyx Storm January 2025), most readers are landing on 2027 as the safe estimate, with a faction of optimists hoping for late 2026. Yarros has also mentioned plotting books 4 and 5 together to make sure the endgame lands properly, which is reassuring for the series and inconvenient for everyone who wants it immediately.

Who is the venin brother at the end of Onyx Storm?

The cliffhanger Yarros left us with: Xaden faces someone he calls his “brother” who has turned venin. Male, knows about Xaden’s own condition, and someone Xaden actually cares enough about to try to save. The identity is being withheld until book 4.

The three leading theories the fandom keeps cycling through:

Bohdi

Xaden’s cousin, near‑identical in appearance, was the person who was by his side through five months of watching him fight his own turning. Throughout Onyx Storm, we see Bodhi struggling. He’s been Xaden’s “shadow” for three books, and in the final battle at Draithus, he realises his signet—which mimics or counters others—is functionally useless against the venin. We’ve seen him “retching” and heaving in Imogen’s POV, a physical reaction we’ve only ever seen in this series when a character has crossed a soul-shattering line. 

Bodhi didn’t turn because he was evil. He turned because he’s watched Xaden struggle alone for five months and thought he could help by bearing the burden too. He likely channeled to save Xaden or Sgaeyl, thinking he could control it. Xaden and Violet’s immediate, secret wedding in the “missing 12 hours” wasn’t just romantic—it was a legal necessity. If Bodhi is venin, he is disqualified from the Tyrrendor throne. By marrying Violet, Xaden ensured the dukedom passes to her, keeping the rebellion’s power base out of venin hands.

Garrick

Garrick is the heart of the rebellion and Xaden’s lifelong “brother” in every way that matters. The Swoon analysis notes that Garrick actually uses the specific word “brother” to refer to Xaden in the bonus Iron Flame chapters, which makes the “new brother” framing in the Onyx Storm cliffhanger feel like a direct, agonizing callback. If Garrick turned, it wasn’t for power—it was because he’s spent his life protecting Xaden’s secrets, and he likely channeled to save Xaden from a Sage’s killing blow.

The counter-argument often seen in the r/onyxstorm threads is that this would be too narratively redundant since we already have a turned lead, but that’s exactly why we’re worried. Losing Garrick to the venin hunger would strip Xaden of a link to his humanity. It would force Xaden into a position where he has to lead the venin while the one person who truly knows his soul is slowly losing his own.

Aaric 

Aaric is the “tragic” candidate in this lineup. The Swoon breakdown suggests that Aaric’s new precognition signet gives us the answer; if he saw a future where the only way to stop a total Continental collapse was to infiltrate the venin from the inside, Aaric is exactly the kind of self-sacrificing royal who would do it. 

By becoming a sacrificial venin, he would be able to feed Xaden and the other rebels information from deep within the Sage’s inner circle. It turns the brother reveal into a high-stakes espionage plot. But I argue it’s more likely his power will be used in some way to help Violet, setting it up as a decision for the main character would give the power more oomph and feel less convenient. 

Brennan

Fewer people actually think that Brennan might be the brother, because “brother-in-law” and all. As the Mender and leader, he would be really difficult to overcome as a villain. If Brennan did turn, it might be tied to his previous death and resurrection. The Swoon theory posits that the magic used to bring him back left a hollow in his soul that the venin hunger finally filled. If Violet loses her brother for a second time, that wouldn’t be ideal, and would up the stakes.

Want to deep dive this one?

• Swooon: “Onyx Storm Theories: Who Is Xaden’s New Brother?” for the full breakdown of each suspect with evidence.
• Screen Rant: “3 Onyx Storm Theories About Who Xaden’s New Brother Could Be” for a tighter summary of the top three.

What actually happened during Violet’s missing 12 hours?

Ok so here is the rundown…Violet asked Imogen to erase twelve hours of her memory after the battle at Draithus. She woke up married to Xaden, with six dragon eggs missing and several dragons dead.

The main theory is that the memory wipe was actually to protect everyone from something. If Violet doesn’t know Xaden’s plan, or where he went, then the Sages and the venin cannot pull that information out of her during torture.

But what could that secret be?

Is Xaden going to be the villain of book 4?

Rebecca Yarros has teased Xaden’s villain era, and the end of Onyx Storm, he’s gone, he left a don’t look for me letter, and he is fully venin. So this may mean that we’re finally there, but I think we’ll have some of the book where he’s not an enemy, as there is still a part of him fighting for Violet. I wonder by the end of or mid-book 4 if that’s when he’ll fully lose himself and turn. Maybe he’ll think Violet has died? Maybe he’s simply tired and can’t hold on any more. There has been hints of this happening all throughout the book as a theme in general.

What that probably means for book 4’s structure:

• A split‑POV or multi‑POV narrative, since Violet and Xaden are no longer in the same location or the same side of the war we’ll need both sides, and we’ll need to see Xaden becoming evil.
• Xaden operating outside the alliance, possibly working with venin, possibly working against them from inside, possibly losing himself entirely to the hunger.
• Violet being the one left running Tyrrendor’s political situation (they’re married, she has legal standing now in ways she didn’t before) while also trying to find him, fix the wards, and not let Tairn know how scared she is.

The villain era framing from Yarros suggests he will do things in book 4 that are hard to justify from the outside, which makes this far more interesting. Could this mean Xaden really turns on Violet in some way? See what else people are expecting here.

The W‑pattern theory? Book 4 is going to be the lowest point

This theory has been circulating since Onyx Storm dropped.

The emotional arc of the series so far:

• Fourth Wing — High. Brennan is alive. Dragons chose her. They’re together.
• Iron Flame — Low. Xaden is turning venin. The wards are failing. Nobody can be trusted.
• Onyx Storm — Relative High. Married. Wards restored. A plan exists.
• Book 4 — Predicted low point. Everything falls apart before the final book rights it.

If the W holds, book 4 is the floor before book 5 is the resolution which maps onto Yarros’s Xaden gets worse before he gets better confirmation and her warning about a major character death coming.

Reddit threads tracking this pattern are generally expecting that the death will dismantle Violet’s inner circle, Xaden might be the cause, and a cliffhanger that is somehow worse than what we have. If you’re curious about all of your favorite series and how authors map them out you can check out this blog on Why Book 2 Is Always The Worst, which breaks down series order and what to expect from each book.

Does Violet have a third signet?

Now we know her second signet is dream‑walking (thanks Andarna), the fandom is already looking ahead.

The leading theory is that Andarna’s gift isn’t a traditional combat signet but Power Manipulation or Source‑Tethering, tied to her seventh‑breed status.

If Violet can interact with the Source itself, she may be the only person capable of re‑wiring what venin have corrupted, which loops back to the Xaden cure conversation and the living wardstone theory. You can see more in this part 1 of the Fourth Wing prediction series or part 2.

The book 4 survival checklist

Everything Onyx Storm set up that book 4 will have to deal with so you can keep track.

• The marriage. Violet is Xaden’s wife and Tyrrendor’s duchess by law. She has political standing she didn’t have before, which makes her both more powerful and a much bigger target.
• The missing eggs. Six dragon eggs were not accounted for after Draithus. If the venin hatch them under corrupted conditions, the alliance is fighting venin dragons.
• Tairn and Sgaeyl. Tairn is in a deep rest cycle. Sgaeyl left with Xaden. The mating bond between them cannot survive indefinite separation under the series’ own lore. If Sgaeyl has severed or suppressed her tether to protect Tairn, he may wake up pretty ticked.
• Violet’s missing memory. Twelve hours of her life are gone, by her own choice. Book 4 will have to decide what she finds out and when.
• The major character death. Yarros confirmed it but who is it?

Want more?

• Part 1: Onyx Storm Theories That Might Actually Be True
• Part 2: The Wildest Empyrean Theories Fans Still Can’t Let Go Of | Is Violet a Dragon?
• More Books Like Fourth Wing to Hold You Over

FAQ: Fourth Wing book 4