Aries

Aries is a Celestial Spirit that is one of the 12 Golden Zodiac Keys. Her key is currently owned by Lucy and it used to be owned by Angel and Karen Lilica.

History
Aries is a timid female that Karen, a Celestial Spirit mage, used to do many horrible things for her such as used her as a shield (because apparently she has no fighting abilities) and used her to lead away all of her boyfriends. It is revealed that Angel murdered Karen and took Aries' key, although Angel doesn't seem to treat her any better, seen when Angel shoots through Aries to hit Loke with Caelum.

Loke arc
Three years ago, Aries was a Celestial spirit owned by Karen Lilica. In Loke's flashback, Aries was treated horribly by Karen. She used her to keep her "boyfriends" away from her. She tries to protest but she is too intimidated by Karen. Bob sees what happens and warns Karen to take care of her spirits. In a rage, she accuses Aries of squealing on her to the guild master. She threatens to keep Aries in the Human world for a week, but before Karen can torture her, Loke steps in and tells Karen to break her contracts with Aries and himself. When she refuses, Leo threatens to remain in the human world until she agrees, rendering Karen unable to summon any other Celestial Spirits. Karen continues to refuse, since she believes that he cannot remain in the human world for a long time; however, Leo leaves her with the ultimatum and goes to a deserted chapel where he stays for three months, attempting to get Karen to break the contracts. When Leo returns, he learns that Karen was killed on a mission and that Aries' key was taken.

Oracion Seis arc
After an exchange in spirit, Aries is summoned to battle with Loke and Lucy Heartfilia. Despite the two not wanting to fight one other, they chose to fight for the sake of their pride, and the battle begins. However, due to Aries' non-combative nature, she fights a losing battle to Loke. As the battle progresses, Angel summons Caelum and uses it to blast through her and hit Loke, causing them both to return to the Celestial World for healing. After her defeat, Angel is arrested and her contracts with her spirits are broken. Aries, along with Scorpio and Gemini, seek out Lucy and form contracts with her instead.

Edoras arc
Lucy summons Aries to prevent the Edoras soldiers from capturing her and her friends. Aries then proceeds to attack the soldiers with a technique called "Wool Bomb", which allows Lucy and company to escape.

Magic and Abilities
Aries uses Wool Magic in battle.
 * Wool Bomb (ウ－ルボム Ūru Bomu) - Aries unleashes a cloud of wool at enemies, which apparently makes them go into a relaxed state.

Trivia

 * Her outfit has changed as the story progressed. In her very first appearance, Aries did not have a Fanny Pack on her waist, and her neck was covered in white wool rather than the black wool shown in her recent appearance.
 * Happy calls her Fluffy as seen in chapter 172.
 * Out of the known Celestial Spirits, she is the one that has the most total owners.