Grey Mourner's real name is Ze'mer. She used to be one of the Five Great Knights of Hallownest. She is not originally from Hallownest, being native to an area outside of the kingdom known as "lands serene". It is from this place that she also brought Delicate Flowers.
The daughter of the Traitor Lord was her lover, but the mantises denied their union, rejecting Grey Mourner due to her being an outsider. Some time after her Mantis lover died, Grey Mourner retreated to her house in the Resting Grounds where she turned to mourning.
Grey Mourner is found in the east area of the Resting Grounds, behind breakable walls. Reaching her requires Desolate Dive or Descending Dark.
She talks about her dead lover and requests that the Knight takes a Delicate Flower to her grave, located in the Queen's Gardens. This flower breaks if the Knight uses the Stagways, teleports with the Dreamgate, or takes damage.
She dissipates after successfully completing this quest, leaving behind a Mask Shard.
Ahhhh.... Me'hon. This world. This cruel, sinful world. Why does che' wake? Why does che' persist? Ahhh Le'mer, you could not know of tragedy as complete as che's, true lovers stripped apart, two worlds that could not meet. And now meled'lover, dead so long in time. Dead, so far away. Buried, moina? Ai.
Amongst its hateful kin that did deny our union, that did reject che's... outside-ness. She doesn't suppose?... Nahlo, Nahlo. Could che' ask? Could che' burden? Le'mer, woulds't you, coulds't you deliver gift to her grave? The gift is, maybe small?
But the trek is long. She rests amongst her kind near our Queen's lush refuge. Would such a thing be done? Che' asks perhaps impossible things? Mad things? For Le'mer to take up such quest would be a kindness che' has near forgotten.
You turn away? Che' should've expected such. This world is not one of favours. Only of heart-ache.
Rare boon you grant Le'mer. It will be che's last request. After this, never shall che' lay burden on another. A sacred flower is the offering. It is a rare, delicate object. One of a kind. You must cherish it, must act as though it were your own heart. If you were to get hurt whilst carrying it, or did to attempt ride those jolting transit beasts, it would forever be destroyed.
Her grave lies in the middle of the Queen's overgrown estate. It is surrounded by her kind, who will not look kindly on your trespass. Take care Le'mer. My hopes I place upon you and my fervent wish that this small solace may come to pass.
Listening while having flower
Her grave lies in the middle of the Queen's old retreat, a far journey from here and the roads between are fraught with beasts. Safe tiding on your journey. My heart does flutter to feel such kindness from so tiny a creature.
Failing to deliver flower
Ulll Waaaaii! Che's sacred, precious, one of its kind flower. Ruined. Che's love, denied her final gift. Such suffering for che'. Such misery. Che' thought she could bear no more.
...I suppose, che' does have one more flower though. But Le'mer! This one is equally sacred and equally fragile. Where'st one to accept such quest, it must become mel'precious heart. Would such a thing be again be tried?
Accepting flower after it was destroyed
Me'hon? Does the heart beat a moment? Share pain of grief and hope to soothe it? Would you convey che's final gift unto her lover's grave?
Offering flower again after it was destroyed
Then this new, sacred, one of its kind flower che' shall give you. As che warned before, it doest become precious as one's heart whilst held.
If you were to get hurt again whilst carrying it, or did to attempt ride those jolting transit beasts, this one too shall be destroyed. Though my faith in one has been...challenged, my hopes are still with you Le'mer.
Listening while having flower after it was destroyed previously
Her grave lies in the middle of the Queen's old retreat. It's a far journey from here and you've already learned how dangerous those paths can be. Be safe...And be more careful. Me'hon.
Failing to deliver flower again
.....Wai. Destroyed. Again. Another rare and precious thing reduced to wilted stem. Che' does have spare...But Le'mer must know, a precious, sacred fragile flower it is. She did not want to part with it, but for meled'love, she would give all. Woulds't that quest again be taken?
Woulds't you perhaps attempt the journey to che's lover's grave again?
Mi'? Le'mer, you have done this thing? Is it possible? This world's cruelty, I'd thought it overwhelming, but le'mer, such great compassion. That Che's love would know her partner's heart even aeon past.
Is it that, Le'mer? Such grief, can end? Che' can end? Ullll, eh nai dear love. Che' too can end.
Ulll... Nemenoo... Nails and claws... Why must it be so?
Grey Mourner is found residing in a house in a hidden area in the east of the Resting Grounds. The ceiling above a chest needs to be broken to access her location. Her residence is referred to as the "Grey Mansion" on the physical map.
Grey Mourner has one line of cut dialogue which would have been triggered by obtaining the King's Brand. However, this line is not used in the game nor in Grey Mourner's dialogue programming:
Le'mer, takes that heavy mantle...Che' wouldn't wish it upon one. Having served that brand at its great height, che' knows well what suffering it brings. Enough to turn nym'King to flee or fair Knights to mourning.
↑Her silhouette is visible during the White Defender fight, which takes place in a memory of Ogrim of his time in the Pale Court. Ogrim also makes a dung statue in her likeness, along with statues of the other Great Knights.
↑ 3.03.1White Lady when she is given a delicate flower: "Far it travelled to reach this place, brought by one beloved, fair knight of lands serene."
↑Grey Mourner: "And now meled'lover, dead so long in time. Dead, so far away. Buried, moina? Ai." "Amongst its hateful kin that did deny our union, that did reject che's... outside-ness."
↑Grey Mourner: "Is it that, Le'mer? Such grief, can end?"