Alicia Rue is the leader of the Cait Sith. She was elected by popular vote. She is also training her dark magic capable of using Moonlight Mirror. She forms an alliance with the Sylphs to finish the Conquer the World Tree Quest.

Spoiler

During the meeting with Sylph , the groups are attacked by Salamanders lead by General Eugene. Kirito dives in to save the day and fights off Eugene although Kirito has inferior equipment. Later, along with Sylph reinforcements, she aid Kirito's ascension of the World Tree after using collected funds to purchase armor of at least Ancient grade for all of her warriors.

(Source: SAO Wiki)