Writer's Chair
One of the Seven Wonders of the OGing World, the Writer's Chair (sometimes known as the Author's Chair) gives the one sitting in it the power to manipulate R-Space in accordance with their imagination, similar to S-Space. The chair was in fact used by Eerie II in order to seal away Eerie I eons ago, before the senior Eerie could destroy the universe. Its power sealed by four stones, the chair was passed down through the millions of years until it ended up on the Planet of Sharp, Dangerous Objects. Like the Eeries, the chair is a metaphor; it represents and bestows the creative potential of those in Q-Space, but is only as useful as any other chair (that's sealing an ancient, god-like creature) without the stones.
Good Timeline
It was discovered and brought to Earth as an inaugural gift for Ditto McCloaker along with the stones. Bat-Ear Mirawk was assigned to guard the chair by the Authors and became a secret serviceman to accomplish this goal. However, the combined efforts of SteveT, Wario Jr., WarioFan 13, and Lobsterio (but mostly SteveT) were enough to defeat Mirawk, and the chair was taken to be used in Old Golem's scheme to revive Luigi 64 and Isis.
In the alternate future, Flutter was given the chair in exchange for obedience to Golem and Luigi 64. He used it to give himself the power to decapitate people, while the chair itself was dumped in one of his secret labs. It is collected and combined with the other plot devices to inadvertently release Neely from his prison, then used by Big Al to backhand Old Golem into the afterlife.
Returning to the present, the chair is used again by Flutter to combat Neely. Upon the conclusion of the battle, it and the other plot devices are regathered by the elemental warriors and taken to secure locations.
Bad Timeline
It was found by Ritz who, unable to break the seal, instead broke off one of the legs and carried it with him; the leg was able to block S-Space abilities. The incomplete chair reverted into a human named Key (presumably a manifestation of Eerie).
In Member OG 10: Full Circle, Nijuka attempts to acquire the chair with Dark Cloak and Akujin no longer holding him back. When the four stones gather on the planet Mystery, along with Key and the broken leg (Stic), Key transports them back to the Planet of Sharp, Dangerous Objects along with Nijuka and Introbulus. Nijuka sits in the chair, but rather than gain its powers he releases and is possessed by Eerie. Introbulus then uses the chair to decapitate Nijuka. When one of the stones is stolen back by Lupus, the chair is left behind on the planet by the Eerie-possessed Introbulus, who had intended to use its power to restart the universe. Since he is defeated before he can return for it, the chair is ultimately forgotten.