The Warren is a location in Neithernor. When Deirdre first traveled to Neithernor, it is where she arrived.
According to Deirdre Green, the warren was like one of those stories where animals had houses, just like people. The walls were made of soil, but packed tight and rubbed smooth. The floor was made of stone and nearly covered with overlapping mismatched carpets. There was a hearth charred by old fires. A wind down the chimney had blown cold ash across the carpets. The room was subterranean, but warm. There were ornate dressers and worn chests. The door to leave the warren was barred and broken, with dirt and pebbles scattered underneath it as if a landslide had slammed it shut. There was only one window. Its frame was a tangle of knotted roots that grew out of the top of the wall and wreathed the opening. It was too small to climb through. There was a narrow bed, which was unmade, and a small glass and metal lantern on the table beside it. There were paintings hanging on the walls: landscapes, seascapes, shorelines, and wooded paths. There was a painting of a chain of low islands in an ocean, and in their center was what looked like a dozen shipwrecks smashed together: crow’s nests on masts, along with bows and sails, made a sort of looming castle in the middle of the sea.
Deirdre first described encountering the warren in her blog post, “My Mother’s Daughter,” when she knocked into Neithernor for the first time. Knocking on the brownstone’s door had led her to a broom closet in the warren, which she realized was thick with magiq. She fell asleep in the warren before knocking back into the mundane world, where she found a much shorter amount of time had passed. Deirdre learned that she had gained the power to summon a knocking door at will, allowing her access to Neithernor.
The trip to the warren had unlocked a new journal entry, in which Sullivan Green described his pursuit of Neithernor and his life fleeing the Storm. He eventually found his way to Central Park, where he found the Storm couldn’t follow him. A door to Neithernor existed there, as well as the dying Council of the 18 Gates. Together, the two grew stronger and devised a plan to open the Book of Briars and stop the Storm once and for all. Sullivan had placed his hopes in Deirdre, saying he knew that she would find her way to magiq because she was her mother’s daughter. He told her to explore Neithernor and to take his walking stick with her, which he had placed near the warren’s bed.
After reading the entry, Deirdre and Cole had their first fight, because Cole didn’t want to stay in the warren because it reminded him of a traumatic time from his childhood. Deirdre and Cole parted ways, with Deirdre continuing to explore Neithernor.
The warren acted as a secure place for Deirdre to return. In her post, “The Three Manners of Magiq,” Deirdre noted that she spent two nights there, spending the whole day watching the sky from the window. She attempted to open the door to the warren but found that it was stuck.
In the post “Mr. Wideawake,” Deirdre received a note that told her to meet them in the warren. Thinking it was Cole, she knocked in, but was surprised by a human-sized sooty tern bird named Mr. Wideawake. Mr. Wideawake told Deirdre that he was the current Collector for The Monarchs and that if the Council and the Mountaineers were wiped out, he and his associates were the last things standing between the Silver and complete control over magiq.
He explained to Deirdre that the Book of The Wild had been altered to erase magiq, turning into the Book of Kings in the process. Mr. Wideawake told Deirdre that the reason he was there was that the Monarchs wanted to preserve The Little Red House at any cost and that they wanted to stop the Mountaineers, who were planning to exchange it with the Storm for the Book of Briars so that they could study it and understand how it fit into the changes made in the Book of Kings. The message was actually a warning to Deirdre that the Monarchs were coming for the book, since they knew where to find it and how to access it from reading her blog post.