Which acrobatic fighter joins Azula's team in Book Two?

The acrobatic fighter who joins Azula’s team in Book Two is Ty Lee.

Ty Lee is a Fire Nation performer and an exceptionally agile martial artist. She grew up in a large family and joined a traveling circus because she wanted an identity separate from her many identical-looking sisters. Her circus training explains her flips, balance, speed, and ability to attack from unexpected angles.

Azula recruits Ty Lee after finding her performing with the circus. Ty Lee initially hesitates because she wants to remain with her troupe, but Azula’s intimidating presence persuades her to join the hunt for the Avatar. Ty Lee later uses chi-blocking, striking pressure points to temporarily disable an opponent’s bending and movement.

A common mix-up is confusing Ty Lee with Mai, who joins Azula at the same time. Ty Lee is the cheerful, acrobatic fighter; Mai is the gloomy noble who specializes in throwing knives and other sharp projectiles. The two become Azula’s closest companions during Book Two.