Not main deities themselves, Qian Li Yan and Shun Feng Er usually appear as Mazu's companions and guardians. While their status in the Taoist pantheon is quite low, their very special skills make them stand out.
There are various stories about the origins of these two, but most agree that they were brothers and warriors, the older having the gift of extraordinary vision, and the younger of extraordinary hearing. In one common telling, they lived during the Shang Dynasty of China (商朝, Shang Chao). Due to their amazing skills, they joined the army of the Shang, who were fighting the rival Zhou (周), and became invaluable spies. The older brother could spot troop movements from many miles away, while the younger brother could hear the enemy generals discussing their war plans and giving orders. Naturally, this gave the Shang army a huge advantage in the war between the two.
Desperate to counter this advantage, the Zhou had the idea of blocking the brothers' skills, and one day their men were ordered to line up, waving flags and banging drums. When the brothers went to spy on the enemy camp that day, the older one's vision was blocked by the flags, while the younger's hearing was drowned out by the drums. Having lost this crucial source of intelligence, the Shang army was put on the back foot, and the brothers were killed in a bloody battle. The Zhou went on to succeed the Shang as China's next dynasty, and the brothers' violent deaths left their spirits tied to the place of their death, a place called Peach Blossom Mountain (桃花山). They became bored, and their spirits became vengeful, terrorizing the local people.
Hearing of the plight of the brothers' victims, the goddess Mazu (Matzu, 媽祖) decided to help them, so she travelled to the mountain where the brothers lived. Confronting them, her far superior power easily overcame them, and begging for their lives to be spared, the brothers promised to reform, and to serve Mazu. Agreeing to this, Mazu took them as her companions, forbidding them from evil and using their abilities to help her.
A second story also involves the brothers dying in war, whilst protecting their families, and becoming restless and hostile spirits who harassed the local people. One day they saw a woman walking, and decided to play a trick on her, but as she approached they realised how beautiful she was, and planned to force her into marriage. However, the woman was the goddess Mazu, and she easily defeated them, forcing them to serve her.
Qian Li Yan, 'meaning thousand miles eye', is the older brother and has the gift of incredible vision, with the ability to see across vast distances, as well as, according to some stories, the future. In Taiwanese culture, he is generally depicted as a green demon with his hand over his eye, scanning the horizon, and armed with an axe. The visually gifted of the two is also sometimes called the Fine Water General (水精將軍, shui jing jiang jun), referring to the legend that he can drink vast amounts of water, even preventing floods, and thus is often shown with his mouth slightly open and his fangs showing. His younger brother, whose name means 'with the wind ear', is generally red, sometimes with a finger in his ear, and holding a halberd. He is also called the Fine Gold General (金精將軍, jin jing jiang jun) as he is believed to consume gold, but as this ability has no use, unlike his brother, he keeps his mouth closed.