Lan Fan is one of two bodyguards of Ling Yao and the granddaughter of Ling's other bodyguard, Fu. She is very quiet and cares deeply for Ling. As a result, she is constantly thinking of his safety and often forgets her own. Lan Fan is a very skilled fighter and is able to sense the presence of a soul (referred to as chi); thus she can quickly identify Homunculi like Envy that have more than one soul in their Philosopher's Stones (meaning she can easily see through Envy's disguises). Although we are never told her age Ling refers to her as a "girl" so we can assume that she and Ling are around the same age.
After being heavily injured by the Führer himself, Lan Fan sacrifices her arm to help Ling and herself escape. Later, She leaves with Fu to have an automail arm made for her. Lan Fan comes back six months later with an automail left arm. The automail is equipped with retractable blade starting from her elbow and ending around her shoulder. She uses it in a fight against Gluttony and in the siege of Central.(Source: Wikipedia)