Caer Suibhne is the ancestral seat of the Suibhne family, the Earls of Douglas. Situated within the mainland of Dael Riata, it is historically regarded as neutral ground suitable for high-level noble negotiations.

Caer Suibhne is in the story “The King's Peace”

• First appears - “The King's Peace,” a standalone short story detailing Dael Riatan politics
• Function: The castle serves as the primary setting for the climax of the story, where a diplomatic dinner intended to secure the “King's Peace” turns into the infamous massacre of the Murchadh leadership.

Caer Suibhne rises from a rocky island in the middle of a fast flowing section of the River Douglas. The main keep is built directly out of the rock, surrounded on all sides by fast flowing water. Over generations the rocks in the river have been artfully placed to make any attempt to cross in boats very dangerous. There’s a wider curtain wall around Caer Suibhne, enclosing a small township of those that support the keep. It sits mostly on the Northeastern bank of the river, and is joined to the keep by a wooden bridge, which raises overnight. There is no safe access to Caer Suibhne other than through the bridge. Either side of the castle the hills are steep, and the ground uneven on them. The only way to progress further up river is to pass by the castle itself, or under the fall of shot from the catapults on the battlements, or the archers stationed beside them. A small battery on the Northwestern cliff ensures that nothing could sneak by. That battery is even more impregnable than the keep of Caer Suibhne, it sits atop a 200 foot sheer rock cliff, access is via a winding path that is in full view of the defenders and the main Keep. Heavier items, including provisions, are hauled up the rock by a rope windlass operated by the catapult crew and the guards.

Caer Suibhne is a substantial stone castle featuring a Great Hall dominated by a large fireplace with wood panelling and flagstone floors. The castle is large enough to contain multiple corridors patrolled by guards and dedicated royal apartments for visiting monarchs. During the events of 774, it was the site where the rules of hospitality, traditionally sacred to the Suibhne family, were bloodily violated when Domnhall Murchadh and his brother Fearchar were killed in the Great Hall.

Notable people

• Alasdair Suibhne: The 7th Earl of Douglas and the host of the fatal 774 negotiation.
• Alasdair V: The King of Dael Riata, who claimed the Murchadhs attempted to assassinate him in the castle.
• Iain Alpin: The King's Steward and Commander of the Lifeguard who executed the Murchadh brothers within the hall.
• Domnhall Murchadh: The 5th Earl of Uisdean, killed here by Alpin.
• Fearchar Murchadh: Brother to Domnhall, also killed during the negotiation.
• Mister Soutar: An official or castellan for the Earl of Douglas who manages castle retainers

• Douglas: The Earldom where Caer Suibhne is located.
• Dael Riata: The Grand Duchy that encompasses the Suibhne lands.