Ere the crossing of the Teleri into Beleriand, Celegind and Alagur, both unbegotten elves, had a son, which they named Thangur, for they both predicted that he would be of righteous heart, a bastion of hope, and a light to all to turn to when needed. After the Noldorin Elves left for Valinor, and the Teleri Elves put to a stop to wait in Middle-earth, Thangur was taught much in this period, mostly that of what his parents had come to know, his father Celegind, had starting to teach him herb-lore, for Celegind was a Elf of nature, and started to grew attached to Beleriand, Alagur, had done the same, teaching him of herb-lore as well. Thangur was quickly being taught in the ways of nature, for much like his kin, his love for forests burn brightly. In the 200 years that Elwë was gone for, he learned much, his mother taught him in the work of heraldry-making, and the other acts of seamstresses. When Elwë returned with Melian, gathering his people and founded the Kingdom of Doriath, Thangur and his family started to feel glad that they hadn’t went to Valinor, and stayed in the green forests and fields of Beleriand. Ere the caverns of Menegroth were carved by the Dwarves, they lived in a home with a oak tree growing through the middle of it, near the River Esgalduin, once the Dwarves were finished with their task, hearing the splendour of the caverns, the family decided to join the rest of their kin in the city, yet they were reluctant, for they had grown accustomed to their home and they were living in the forest. It was by the fierce desire of Thangur’s that convinced them, and soon, they found their home in Menegroth. Here it was that Celegind decided to teach Thangur to be a scholar, to record and preserve history. It was here also that he was taught swordplay and how to handle a shield in combat by his father. These teachings served him great purpose in the Battle of the Thousand Caves, where Dwarves killed King Thingol, took the Nauglamir, and attempted to retreat back to their home, but were slain, having only two Dwarves survive and tell lies. They told their kin that King Thingol had slain the Dwarves, refusing to pay for their work, and soon, the Dwarves attacked Menegroth, slaying many Elves. Thangur proved his father name true when he slew three Dwarves that attempted to slay his father, mother, and some of the younger elves.

After seeing that the captains had scattered, he lost hope, and directed his family and some of the elves out of Menegroth, where they fled into their old home. It was there that they made sure everyone was alright, yet the inspection was cut short as three more Dwarves followed them. With haste Thangur slew them. It was decided that patience was key, and for a time until Dior, Elu Thingol’s grandson and heir to the throne, had came to Menegroth and became the King of Doriath, once again, Menegroth was their home. Ere the Second Sack of Doriath, the attack led by the sons of Feanor, Thangur had became known as Celechil. His skills in combat was once again put to the test, his father’s skill had waned, while his skill as a scholar waxed. Alagur’s skill in swordplay and archery was sharpened during this battle. The young Elves which he had harboured and grew to become sons of his own fell to the servants of the sons of Feanor in the battle, leaving Celechil struck with grief. Due to this grief, his heart burned with revenge, and he had it, for before their escape to the Mouths of Sirion, he killed a many of the servants.

While dwelling in the Mouths of Sirion, he decided that he would sire now son nor a daughter until three centuries had passed. Ere the Third Kinslaying, he and his family lived in peace, his father continuing to be a scholar, and his mother now being a healer. In the Third Kinslaying, his father fell to the enemy, and his mother fell to poison used by the Elves that aided Feanor and the Sons of Feanor in the Third Kinslaying. After, the Grief that Celechil had seen almost drove him to a mindless slaughter, to avenge his parents, but he did not. He dwelt in the Isle of Balar with the rest of the survivors of the Third Kinslaying under Círdan and Gil-galad’s rule. After the Fall of Beleriand, he went to Lindon, the kingdom founded by Gil-galad. Dwelling there for some time before migrating eastwards to Greenwood the Great. It was there in the Halls of the King that he served as a lore-master, writing and preserving the knowledge which he contained from the Years of the Trees and the First age. It was here that he fell in love with a elleth singer known as Erellir, and had three daughters, Banwith, Sadrochil, and Ferianor. They raised them to be scholars, artists, singers and all, for they wanted their daughters to continue what they had been doing for their lifetime. He was going to head to Eregion to craft rings for his family, yet he was too late, for Sauron had sacked it, leaving only ruins in his departure, he was saddened by this, and his hatred of the darkness only grew more. He spend the rest of the Second Age in Greenwood the Great. Once the Third Age came, and his home now became known as Mirkwood, he decided to act as a messenger and pilgrim, and a scholar. Oft is he found in the Library of Elrond in Imladris, and in Lothlorien, and in Felogoth, Halls of the King in Mirkwood.