Perilous Seat, Seat of Danger
If you want to get rid of someone, make him vow to sit in this, the forbidden seat at the Grail Table and Round Table, meant only for the most pure. It was said to commemorate the seat occupied by Christ at the table of the Last Supper, or the one vacated by Judas at the same table. Robert de Boron was the first writer to mention it.
The Siege Perilous would also be useful to suicide with the maximum dramatic effect. Nobody but Galahad could sit in this chair, and anyone else who tried it was devoured by a column of fire. The Siege Perilous was to be filled by Galahad 454 winters after the Passion of Our Lord. This gives us a date for the era of Malory’s Arthur.
According to the Didot-Perceval, it was the thirteenth seat the Round Table, and Merlin had ordained that only the best knight could sit in it. A newly-knighted Perceval jumped into the seat without thought, and it split under him. The seat had been intended for him, but he had sat in it prematurely. As a result, the Fisher King could not be cured and part of Britain became a Waste Land.
The Vulgate romances relate that at the Grail Table, Josephus (Josephe), the son of Joseph of Arimathea, sat in the Perilous Seat. The Round Table’s Perilous Seat was reserved for Galahad. (It was empty for many years until Galahad came to court at the beginning of the Grail Quest.) Any other man who sat in the Perilous Seat was swiftly incinerated, swallowed by the earth, or carried off in flames. This horrid fate befell Moses at the Grail Table, and Riger at the Round Table. The seats next to the Perilous Seat were likewise reserved for the best of knights: at the Round Table, they were filled by Perceval and Bors.
The Vulgate also tells about one knight, Sir Brumant l’Orguilleus, who came all the way from France to sit in the Siege Perilous. He knew he had made a silly, boastful vow, and wept all the way to the Siege, but a vow was a vow. Lancelot, sitting in the chair next to the Siege Perilous, did not move away when the fire descended, and was not even singed by the holocaust that devoured Brumant.
Analogs to the Perilous Seat appear in other romances. In Durmart le Gallois, Durmart sits in one upon is arrival at Arthur’s court. In Wirnt von Grafenberg’s Wigalois, Wigalois sits on a rock when he arrives at Arthur’s court, which astonishes the other knights because it was said that only a pure knight could even approach it.