Sun Bu'er was the seventh disciple of Wang Chongyang and one of the seven masters of the Quanzhen Sect. She based off a real historical figure.
Sun Bu'er was the wife of Ma Yu before she became a Taoist and was accepted into the Quanzhen quite a while after Ma Yu.
Sun Bu'er's Toaist title is the Sage of Tranquility because of her peaceful sense. She is also the only female Toaist in the Quanzhen Sect. As for her martial arts skills, her and Hao Datong are singled out as weaker than the other masters of the Quanzhen Sect, as they were accepted into the school later. She also teaches Chen Yaojia some kung fu, and she uses it to help Yin Zhiping and Lu Guanying to defeat Hou Tonghai. In Return of The Condor Heroes, it is mentioned that to compensate for her weaker martial arts, Wang Chongyang gave her the finest sword of the Quanzhen Sect. When Yang Guo borrows a sword at the picking of the leader of the wulin, she offers the blade to him, yet he doesn't take it as he does not appreciate the way the Quanzhen Sect has treated him. Instead, he takes a rusty sword from the beggar clan.