Hay Lin's grandmother and the previous Guardian of Air. After the Veil was raised, cutting Earth off from Meridian, Yan Lin kept the Heart of Kandrakar
on Earth until it was time to pass it on to the next generation. After which time she acted as a mentor to the new Guardians, and served as an informal adviser to the Council of Kandrakar.
Upon her return, Nerissa attempted to corrupt Yan Lin by offering her power, youth, and finally the safety of her granddaughter, but Yan Lin refused all three. Nerissa was forced to imprison Yan Lin, alongside Elyon, within the Heart of Meridian. Nerissa then created an Altemere to take her place.
Although the real Yan Lin had the will to resist Nerissa, Altemere Yan Lin's desire to live was stronger than her self control, and she fell under Nerissa's thrall. She even admitted to Nerissa such a fact, adding that she had come to love Hay Lin as if she were her true granddaughter. Altemere Yan Lin's replacement of the real Yan Lin went unnoticed until close to the end of season 2, and up until that point Nerissa used Yan Lin's supposed loss to the dark side to taunt Hay Lin, in an unsuccessful attempt to break her spirit. Nerissa had the brainwashed Yan Lin bullying and fighting her granddaughter, but when she kidnapped and used her boyfriend Eric as a hostage, Hay Lin reacted and fought back.
After being used to fight W.I.T.C.H., Altemere Yan Lin was freed from Nerissa's thrall at the same time as the other members of C.H.Y.K.N., and she was imprisoned alongside them when Nerissa absorbed them.
was excused in her class for the announcement that Yan Lin died and she must attend her burial. The guardians thought that it was final but when they arrived in Kandrakar, they have seen Yan Lin whose spirit remains in Kandrakar to serve the council.
Yan Lin was abducted by the gloomidians for believing that Yan Lin is the light that they have been waiting for so long so she can return their happiness which has been covered by never ending loneliness. The W.i.t.c.h. rescued her and said that there is nothing to worry about.