Mabanaring, Maboagrin, Mabonagrin
Nephew of King Evrain of Brandigan.
Mabonagrain while still a squire served a year as hired warrior to the Count of Lalut. Maybe. Pronouns and entecedents are such that Phyllis Ann Karr see some possibility of the count who hired Mabonagrain being, not of Lalut (who was Enide's mother's brother), but an older brother of Enide's father. While serving this year, Mabonagrain and one of Enide's cousins fell in love with each other and made a pact, she requiring him to vow he would grant her an as-yet-unstated favor whenever she should ask it.
She returned to Brandigant Castle with him, where King Evrain eventually knighted him in the "Garden of Joy". She then explained to Mabonagrain that she wished him to fulfil his vow by staying with her in the same garden until a knight came and vanquished him in armed combat. Soon, the city of Brandigan became renowned for this perilous adventure, and Mabonagrain's strict adherence to her wish produced the adventure called the Joy of the Court, wherein many knights perished - among them Gornemant's son Gurzgri - until Erec arrived and defeated Mabonagrain. Mabonagrain told him to blow a horn and this freed him from his magical imprisonment.
P.A. Karr found nothing in the original wording, as translated by D.D.R. Owen, to require the death of every unsuccessful challenger, and certainly Mabonagrain himself retained his life when defeated by Erec.
Possibly he beheaded all his earlier challengers to prove his good faith, or to discourage future challengers, or to ensure that he would not have to fight any particular knight more than once. In any event, he disclaimed any blame for their deaths on the grounds that he had to keep his knightly word in order not to prove a false and disloyal perjurer, an excuse everyone understood so well that they blamed neither him nor his lady for all those deaths.
On the contrary, both he and she were delightedly drawn into the general rejoicings over his defeat, which celebrations lasted three days before Erec insisted on leaving. Sounding overjoyed at his own defeat, especially when he learned that his conqueror was King Lac's son, Mabonagrain presumably settled down into a fine, socially conscious knight.
He was a foot taller than any other knight known (presumably excluding those of giant blood), and Chrétien remarks on his height as a blemish to his otherwise handsome appearance. He were crimson armor, at least while defending the garden.
As P.A. Karr learned through personal correspondence with Jessica Amanda Salmonson, Mabonagrain would appear to be a descendant or avatar of Mabon, a Welsh god of death, which casts light on both his role in Erec's adventure and the paradisal garden with its fence of impaled heads.
Fairer than Helen of Troy, this damsel was the daughter of Enide's father's brother, and thus another cousin of Enide's. Finding her in the "Garden of Joy" at Brandigant Castle, Enide felt unsure whether she recognized her or not, and finally had to ask. Both had been little more than children when the cousin left with Mabonagrain.
One is tempted to hypothesize that this damsel made her request of Mabonagrain because she wanted to keep him safe with her, secluded in their garden from the violence of the age.