After Balin fought with Sir Lanceor of Ireland and killed him (in turn causing Lanceor's lover Colombe to take her own life), he went on to find his brother Balan, who was also in disfavour of King Arthur. Merlin foretold of a curse that was lain on the brothers, by a damosel, after Balin drew a magical sword from its sheath, thereby laying a fatal curse "on him and his best friend".

Balan, joined by his brother, decide to attack King Rience in order to regain their honour. They succeeded in ambushing the king en route to join Lady de Vance in bed and brought the king before Arthur. This resulted in the alliance of 12 rebel kings, including King Rience's brother, King Nero. The kings were captured or killed by Arthur, along with the help of Balin and Balan.

After the battle, Balan comes across a knight, guarding an island castle. He then results in slaying the knight, thereby falling under a curse that imprisons him to protect the castle from any passersby. Following many adventures, Sir Balin comes across the castle, and is told that he must joust with the guarding knight in order to continue his passage. Balin, however, does not recognise that his opponent as his brother: his brother being in disguising red armour with an unrecognisable shield. The brothers end up fighting to the death, with Balan dying a few hours prior to Balin's own end.

The brothers were buried together on the island by Merlin, whom also left the infamous sword on the island later to be found by Galahad.