Plue

Plue aka Nikora, "The Canis Minor" (ニコラ Nikora) is a Silver Key Celestial Spirit that has no obvious combat abilities and is stated to usually be kept as a pet for low-powered Mages, but is as powerful as any other character in the game Fairy Tail Gekitotsu! Kardia Daiseidou. Lucy Heartfilia seems to use hers, named Plue, as a pet and a comical character. Nikora keys are shown to have been sold for as little as 20,000.

Appearance
Plue is a short, stout white creature (who is commonly referred to as a dog by Natsu Dragneel) with bland eyes and a golden horn-like nose (reminiscent of a carrot, thus giving him the slight appearance of a snowman). His body is often shaking nervously, though this doesn't always occur. He cannot speak besides saying "puu-puun", although Natsu seems to be able to understand this. He mostly communicates by using gestures and motions which Lucy finds adorable.

Personality
When Lucy first contracted Plue, he only agreed to be summoned on Tuesdays and Thursdays. Later, however, Plue is available anytime, often appearing at times other than his initial contracted days. Because he is not designed for combat, he serves as a cute pet for his master instead. Plue enjoys sweets and shares a close friendship with Happy. Their good relationship could be accounted for the fact that they are always together during Team Natsu's missions, as well as their almost similar attitudes. Happy and Plue often tease Lucy and Loke.

Daybreak arc
In order to show Natsu and Happy how contracts with Celestial Spirits are made, Lucy summons Plue for the first time and demonstrates it to the two. However, because of Plue's peculiar appearance, Natsu and Happy saw him as a failure. When Plue "speaks" for the first time, Natsu seems to be able to understand him, whereas Lucy could not. It is also Plue who first suggested to Natsu that he and Lucy form a team.

Lullaby arc
Plue is seen beside Lucy when Mirajane tells her to go along with Natsu, Gray and Erza to be their mediator. Lucy carries Plue while seeing Gray and Natsu arguing. Plue is still being carried while Erza discusses the Dark Guild Eisenwald and Lullaby on the train. He is seen soaked when Lucy shakes in fear after hearing about Erigor, saying that she wants to go home and wants no part of it. Afterwards, while on the train, Plue is seen eating along with everyone else.

Galuna Island arc
In a battle against Sherry Blendy, a Mage capable of controlling anything that is not human like puppets, Lucy purposely summons Plue, knowing he will be used against her. Once under Sherry's control, "evil" appears on Plue's forehead, his eyes glow, and he runs aggressively towards Lucy. His noncombatant nature, however, prevents him from harming Lucy despite the flurry of kicks and punches he releases at her lower half. Once Sherry releases the control on Plue, he immediately apologizes to his owner, and returns to the Celestial Spirit World.

Loke arc
After arguing with Loke, Lucy leaves with Happy and Plue, and the latter seems to recognize Loke. Plue is later summoned along with all of Lucy's Spirits in order to persuade the Celestial Spirit King to let Loke return to the Celestial Spirit World.

Daphne arc
Note: Events in this arc occur only in the anime and do not constitute canon material.

Tenrou Island arc
Note: Events in this arc occur only in the anime and do not constitute canon material.

X791 arc
Upon returning to the present time, Lucy heads home with Plue, but was not allowed in her apartment by the landlady because of the seven years of rent she owes. Lucy then talks to Plue about her father, whom she finally decided to visit.

Key of the Starry Sky arc
Note: Events in this arc occur only in the anime and do not constitute canon material.

Grand Magic Games arc
While training for the Grand Magic Games, Lucy and her friends are brought by Virgo to the Celestial Spirit World, where the Spirits, headed by their King, celebrate their return from Tenrou Island. During the festivities, Plue greets Carla and Happy, together with other dozens of Nikora's behind him, who lift the two into the air. Plue then dances with Happy as Lyra plays her harp.

Plue later appears at the King's banquet following the Mages' victory against Future Rogue Cheney's Dragons, and is caught up in the brawl over which guild Yukino Aguria is to join.

Sun Village arc
After returning back to Magnolia, Lucy resumes her everyday life, and this involves summoning Plue and going on walks with him. One day, as Lucy and Plue walk back home, Lucy remembers that she still hasn't paid her rent and says that she needs to go on a mission soon. When Lucy opens her apartment's door, what she and Plue witness is Erza, Carla and Wendy comfortably sitting on her couch.

Magic and Abilities
Enhanced Speed: Plue is shown to have enough speed to dance faster than one of Daphne's Lizardmen.

Immortality: As a Celestial Spirit, Plue cannot die, unless he is somehow forced to stay in the Human World.

Fairy Academy: Yankee-kun and Yankee-chan
Plue, along with other students of Fairy Academy head for their classes during the morning of Lucy's first day at the school.

Megane-Fairy
Lucy lends Plue's Gate Key to Shinagawa, so that the latter may summon Plue in order to demonstrate his ability to perform Magic to Makarov. However, Shinagawa ends up summoning a deformed version of the Spirit instead.

Welcome to Fairy Hills!
Plue accompanies Lucy in investigating a job request from Fairy Hills where they meet Hilda, the client, who assigns Lucy the job.

Happy in Boots
Plue is the first "animal" that Happy captures with his sack and also the first present to the king and princess of the kingdom.

Welcome to Fairy Hills!!
Plue makes an appearance as minor character in the first OVA. Plue accompanies Lucy in investigating a job request from Fairy Hills where they meet Hilda, the client, who assigns Lucy for the job. He later watches as Hilda immediately changes Lucy's normal clothes into that of a cat outfit after Lucy accepts Hilda's strange job.

Fairy Academy - Yankee-kun and Yankee-chan!
Plue appears as the Fairy Academy principal during the assembly called by Carla as a lecture to the delinquent students. He delivers his speech in a dance that is only understood by Natsu and Carla, both moved to tears over Plue's apparently very inspirational spiel.

Fairy Tail Gekitotsu! Kardia Daiseidou
Plue appears as a playable character in DS Game Fairy Tail Gekitotsu! Kardia Daiseidou. In this game, Plue possess the following moves:
 * Main:
 * Sub 1:
 * Sub 2:
 * Sub 3:
 * Super:

Trivia

 * Nikora is the only "dog" Happy likes.
 * Happy plays a trick on Lucy by feigning a voice for Plue. Happy makes a reference to Rave Master, saying that Plue is the servant of a hero with a sacred stone, Haru and the Rave respectively.
 * A special restriction made by Hiro Mashima stated that the number of lines on Plue's nose must be 5, no more, no less.
 * Plue's character was featured in Hiro Mashima's previous work, Rave Master.
 * In the English dub of the first episode, Lucy called Plue's key "Canis Minor the White Dog" instead of "Nikora the Canis minor".
 * In the Manga, Lucy called Plue's key "White Doggy" instead of "Nikora the Canis Minor".