Among the third host of elves traveling to Valinor was a peculiar group, the Undecided Elves, closer in spirit to the Avari, they didn't wish to join the Great March West, yet they did so out of love and loyalty to Elwe and his people, hoping to settle in a definitive decision by the time they reached the Final Shores, however this didn't happen, for Elwe disappeared before the end of their journey and that facilitated the choice of the Undecided Elves, never could they have traded Middle Earth for Valinor, even if the cost was departing with Elwe and their kin, but that cost was not to be paid, for many elves of the third group lingered in Middle Earth looking for their lost leader, and some of them went under the guidance of the Undecided Elves, thus the Twelve Clans were born.
Later Elwe returned as Thingol, and with him came Melian Tóril, the Twelve Clans of Undecided Elves promised him their friendship and loyalty, though no other allegiance could they pronounce, they were free and had no king, Thingol accepted this and generously said they were welcome to live among his people, hence four of the clans stayed in Eglador, the others settling in other places of Beleriand, it was in the realm of Eglador that Merillas was born together with her twin brother and those were days of merriment and joy, her father knew the secrets of the land, soils and stones, while her mother preferred those of the stars deep amidst the sky and Merillas learned enthusiastically from both.
Even at an early age she started to travel the lands of Beleriand, at first escaping from their parents, then with their permission, but always in the company of her brother, and soon she started to draw maps and write texts of wisdom, when others asked her why she did so her answer was always a smile and the same phrase:
"For reasons that are mine but not even I understand"
The years of peace were beautiful but not eternal and soon the enemy returned to Middle Earth, her father died in those years and soon her mother succumbed to grief, during that First Age of the Sun she still travelled, but less than before, after many defeats a host came from the West and the Enemy was defeated, at that moment the elves were offered a second chance to go away from Middle Earth, to decide what to do the Twelve Clans of the Undecided Elves held a meeting and there Merillas spoke in favor of them remaining in Middle Earth, stating that they were Uinoed, the eternally bound:
"Free to leave is whoever doesn't share such spirit, however I know I do, there is no doubt, I am Uinoed and shall ever be"
Upon listening to those words most of her people were convinced and moved east towards southern Eriador and beyond, and since then little has been known or heard from them, the few members of the Twelve Clans that dare wander Middle Earth never telling anything about the destiny of their people.
