Guivret appears after Erec has left the safety of court with Enide and has already been battered by a series of adventures. A small knight rides out to stop him and insists on combat. The stranger is no comic servant and no courtly curiosity. He is an armed ruler who expects every knight crossing his territory to answer his challenge. Erec, already wounded and tired, accepts rather than turn away.

Their fight is long and punishing. Lances give way to swords, shields split and armour takes repeated blows. Erec finally gains the advantage and forces the smaller knight to yield. Only then does the stranger reveal his name: Guivret le Petit. He identifies himself as the king of the country and says that the people of Ireland owe him service in the French poem. Rather than nursing resentment, he offers Erec friendship, men and resources. The duel ends with the two opponents binding wounds and recognising one another as equals.

That promise of friendship matters when news spreads that Erec has died at Limors. Guivret immediately gathers a large force and rides through the night to recover his friend and punish those responsible. The report is wrong. Erec has awakened from his apparent death, killed the count who tried to force Enide into marriage, and escaped. In the darkness the two friends meet without recognising one another. Guivret charges and knocks the weakened Erec from his horse.

Enide's cry reveals the mistake. Guivret dismounts in horror, asks forgiveness and explains that the army behind him was raised for Erec's rescue. He then takes the wounded couple to one of his sisters, whose household provides physicians, rest and clothing. Guivret's role changes completely from challenger to protector. He is no longer simply the small knight who demanded a fight, but the friend whose castles and household become part of Erec's recovery.

Guivret later accompanies Erec toward the Joy of the Court, the dangerous adventure at Brandigan that has defeated earlier challengers. He warns Erec of the peril but does not try to prevent him from pursuing honour. When the adventure is completed, Guivret remains part of the company that returns to Arthur's world. The Welsh romance Geraint ac Enid preserves a closely related Little King, called Y Brenhin Bychan and Gwiffred Petit, who likewise fights the hero and becomes his ally.

Guivret should not be merged with Bilis, the separate dwarf king who appears among the guests at Erec and Enide's wedding. Chrétien presents Bilis as king of the Antipodes and lord of dwarfs, while Guivret enters much later as the small king who fights and befriends Erec. Later scholarship has compared the two figures and discussed dwarf traditions around Guivret, but the romance itself gives them separate names and separate narrative roles.