Here is a profile for Li Ann Tsei, in the format of the Official Handbook of the Marvel Universe:

Name: Li Ann Tsei

Identity/Class: Human

Occupation: Master thief

Group Membership: None

Affiliations: Mac Ramsey (partner), Victor Mansfield (former mentor)

Enemies: Various law enforcement agencies, competing thieves and criminal organizations

Known Relatives: None

Aliases: None

Base of Operations: Various locations around the world

First Appearance: Once a Thief (1996)

Powers/Abilities: Li Ann Tsei is a highly skilled thief with a variety of talents. She is an expert in martial arts and hand-to-hand combat, and is capable of taking on multiple opponents at once. She is also a talented acrobat, able to perform feats of agility and flexibility to aid in her thieving endeavors. Additionally, she is skilled in deception and infiltration, able to convincingly impersonate a wide range of people.

History: Li Ann Tsei was a former protégé of the legendary thief Victor Mansfield, but eventually struck out on her own and became a master thief in her own right. She became partners with Mac Ramsey, another skilled thief, and together they embarked on a series of daring heists around the world.

Despite their success, Li Ann and Mac were often pursued by law enforcement agencies and rival criminal organizations. They also had to contend with the personal and romantic tensions between them, which often threatened to undermine their partnership.

After several years of successful heists, Li Ann and Mac were both offered amnesty by the Chinese government in exchange for stealing a valuable jade artifact. However, the mission turned out to be a trap, and they were betrayed by their employer. In the resulting chaos, Li Ann was presumed dead, and Mac was forced to go into hiding.

Personality: Li Ann Tsei is a tough and determined individual who is not afraid to take risks in order to achieve her goals. She is motivated by the thrill of the heist and the desire to prove her own skill and worth as a thief. Despite her criminal activities, she has a certain code of honor and prefers to avoid violence whenever possible. She also has a strong sense of loyalty to her partners and allies, as evidenced by her close relationship with Mac Ramsey.