Fear Sengar was a Tiste Edur of House Sengar. He was the eldest son of Tomad Sengar and Uruth and a weapon master of the Hiroth tribe (and later of all tribes when they were united under Hannan Mosag's rule). He had three younger brothers: Trull, Binadas, and Rhulad. He was shown as a determined and strongly-willed man and a capable leader of the Tiste Edur armies.
He was described as tall and broad-shouldered, with well-muscled body.
Fear Sengar was betrothed to his beloved Mayen, a beautiful woman from his tribe who accepted the sword he offered her and buried it in front of her door. When the witch king sent the Sengar brothers to claim and bring back the Gift from the Crippled God, it was Fear who led the expedition which successfully reached the sword's location. At the location of the sword and on their way back to the Edur lands, Fear and the group were continously attacked by the Jheck, but managed to escape, mostly due to the heroic efforts of Trull who drew the Jheck away from the others. They did, however, lose Rhulad to the Jheck attack.
Returning from the expedition with the dead body of Rhulad, Fear and Trull were amazed and astonished to witness a dead Rhulad revive and come back to life, as part of a deal he had struck with the Crippled God. Rhulad claimed the position of the Emperor of the Tiste Edur, and Fear was the first to kneel and pledge allegiance to his brother.
Rhulad then asked Fear for a gift, which Fear promised to grant him. Rhulad revealed that he wished Fear's betrothed Mayen as his Empress. Fear allowed his brother to take his beloved, but it broke his heart.
During the Edur conquest of the Letherii, at the Letherii Palace, after Rhulad was defeated by Brys Beddict, Fear could not bring himself to deliver the killing blow to his brother which would have allowed Rhulad to rise again. Instead, Fear fled to Seren Pedac and asked her to be his guide in the search for Scabandari Bloodeye's Finnest.
Fear travelled with Silchas Ruin, Clip, Seren Pedac, Udinaas, Kettle, and Wither. He disagreed with Silchas's constant killing of Tiste Edur, although he had no means to stop him. He had sworn to protect Seren Pedac, since his brother, Trull, had given her his sword, thus making her his betrothed. Despite being told that his dream of finding Father Shadow and restoring Kurald Emurlahn with his aid was impossible, he never faltered until the very end.
When the group reached the Refugium a fight broke out and Fear attempted to stab Silchas Ruin in the back to prevent him from destroying the soul of Scabandari, and realizing Silchas would probably fight Trull. However, he missed and was killed by Clip who sliced his throat with his chainlet. This was witnessed by Trull who remarked on the sad irony of an Edur knife being once again pointed at the back of Silchas Ruin, repeating the ancient betrayal. When Trull said that his brother died a betrayer, Udinaas told him that he was a hero and that the former slave had been proud to know him.