Sir Perimones is the third of the four brothers encountered by Sir Gareth while Gareth travels under the name Beaumains. He follows Sir Percard, the Black Knight, and Sir Pertolepe, the Green Knight, and is followed by Sir Persant of Inde, the Blue Knight.

An important distinction is necessary when identifying him. In Malory’s Le Morte d’Arthur, Perimones is called the Red Knight. Malory states that his horse, harness, shield, spear and everything belonging to him were red. The term Puce Knight does not appear in Malory’s text but is commonly used in later summaries to distinguish Perimones from Sir Ironside, the more prominent Red Knight of the Red Launds.

Perimones is lord of a white tower described as being as white as snow, strongly fortified and surrounded by two ditches. Fifty shields of different colours hang above its gate. Below the tower lies a meadow containing knights, squires, scaffolds and pavilions because a great tournament is to be held there the following morning.

From a window in the tower, Perimones sees Lynette, Gareth and Gareth’s dwarf companion approaching. Recognising Gareth as a knight errant, he decides to ride out and joust with him. Because Gareth is wearing Percard’s black armour and riding his horse, Perimones initially believes that the approaching rider is his brother.

Lynette tells Perimones that the rider is not Percard but the kitchen knave called Beaumains. She reveals that Gareth has killed the Black Knight and defeated Pertolepe the Green Knight. Perimones therefore enters the contest with knowledge that he is fighting the man responsible for his brother’s death and defeat.

The two knights charge with all their strength. Both horses fall during the collision, forcing Gareth and Perimones to continue on foot. They draw their swords and fight for approximately two hours, striking, thrusting and wrestling against one another with great force.

Lynette calls out to Perimones and urges him not to allow a supposed kitchen servant to withstand him for so long. Angered by her words, Perimones increases the strength of his attack and wounds Gareth so badly that blood runs down to the ground. Gareth nevertheless continues fighting and eventually strikes Perimones to the earth.

When Gareth prepares to kill him, Perimones asks for mercy. He offers to yield himself and fifty knights to Gareth’s command and forgives him for the death of Percard. As with Pertolepe, Gareth says that the offer is not enough unless Lynette asks him to save the defeated knight. Lynette intervenes, and Gareth spares Perimones.

Perimones invites Gareth and Lynette to remain at his castle for the night. He provides them with hospitality and orders sixty knights to guard Gareth against any treachery or dishonour. The following morning, Perimones and the same company offer Gareth their homage and permanent service. Malory therefore gives two different numbers within the episode: fifty knights in Perimones’s initial offer and sixty in the later guard and formal company.

Gareth accepts their loyalty on the condition that Perimones and his fellowship present themselves to King Arthur when summoned. Perimones agrees and later appears at Arthur’s court with his brothers.

At Gareth’s wedding to Dame Lionesse, Perimones arrives with sixty knights and performs homage. He asks to serve as Gareth’s chief butler at the wedding feast, and Gareth grants him the office. King Arthur then makes Perimones, Pertolepe and Persant Knights of the Round Table.

Perimones later appears among Arthur’s established knights and fights in the wider conflicts of the realm. Near the end of Malory’s work, he and Pertolepe are listed among the knights killed during Sir Lancelot’s rescue of Queen Guinevere.

Perimones must therefore be kept separate from Sir Ironside. Perimones is one of the four brothers, lives at the White Tower, is defeated before Gareth reaches Castle Dangerous and survives by yielding. Ironside is not one of the brothers; he is the Red Knight of the Red Launds who maintains the siege of Dame Lionesse and becomes Gareth’s final opponent.