Nimue, more frequently referred to by her title The Lady of the Lake, is an alternate reality version of Amy Rose encountered by Sonic during Sonic and the Black Knight. She is a skilled enchantress, and former guardian of the sacred sword Excalibur.
At Merlina's behest, Sonic and Caliburn journey to Nimue's home in Deep Woods in their quest to determine how to blunt the power of Exaclibur's scabbard. Sonic is predictably unnerved by the Lady's resemblance to his long-term stalker, but Caliburn remonstrates the hedgehog and they enter the laketop pavilion.
Nimue blames herself in part for the present dire state of the Grand Kingdom, as she was the one who initially gave Excalibur to King Arthur, only for the power of the scabbard to corrupt the once-noble King. She agrees to help Sonic only if he can prove himself a true and honourable knight who will not be similarly bewitched, and assigns the blue blur three tasks to demonstrate his chivalry.
After Sonic has completed the first task, liberating King Arthur's prisoners in Camelot Castle, Nimue magically disguises herself as a distraught child whose fellow villagers have been kidnapped by a dragon. The hedgehog's heroism in saving the Arthurian folk convinces the Lady of Sonic's just intentions, and she divulges how to negate the scabbard's power using the sacred swords wielded by the Knights of the Round Table.