Lynette and Lyonesse

In some versions of Arthurian legend, Lynette (alternatively known as Linnet, Linette, Lynet, Lynette, Lyonet) is a haughty noble lady who travels to King Arthur's court seeking help for her beautiful sister Lyonesse (also Linesse, Lioness, Lionesse, Lyones, Lyonorr, Lyonors), whose lands are besieged by the Red Knight.

The young Gareth picks up the quest, eventually marrying Lyonesse, while Lynette becomes the lady of his brother Gaheris.

They are most famously depicted by Thomas Malory in Le Morte d'Arthur, where they are sisters of Gringamore (Guinguemar) from Avalon.

Gareth slays the Black Knight, incorporates the others into Arthur's court, and rescues Lynette's sister Lyonesse.

Gareth later counsels Lyonesse to report to King Arthur and pretend she does not know where he is; instead, he tells her to announce a tournament of his knights against the Round Table.

Lionesse by Arthur Rackham for Alfred W. Pollard 's The Romance of King Arthur and His Knights of the Round Table (1917)
Arthur Rackham: "Sir Gareth battling the evil Red Knight while his Lady Lioness watches on" (1917)
"The lady Lyoness ... had [Gareth's] dwarf in examination." N. C. Wyeth 's illustration for The Boy's King Arthur (1922)