Plue

Plue a.k.a Nikora The Canis Minor is a Celestial Spirit that has no obvious combat abilities and is stated to usually be used as a pet for low powered wizards. Lucy Heartfilia seems to use hers, named Plue, as merely a comical character for his summoner. Nikora keys are shown to have been sold for as little as 20,000 Jewels.

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. 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 to be adorable.

Personality
When Lucy first contracted Plue, he only agreed to be summoned on Tuesdays until Thursdays. As the series progressed, however, it was shown that Plue is available anytime. Because he was not designed for combat, he serves as a cute pet for Lucy instead. Plue enjoys sweets and has a close friendship with Happy. Their good relationship could be accounted for the fact that they are always together during Team Natsu missions, as well as their almost similar attitudes. Happy and Plue often tease Lucy and Loke.

Macao 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.

Galuna Island arc
When battling Sherry Blendi, who is capable of controlling her spirits, Lucy deliberately summons Plue, knowing Sherry would control him. Once controlled, "evil" appears on Plue's forehead and, with glowing eyes, runs aggressively towards Lucy. However, his attacks doesn't harm Lucy one bit, leaving Sherry confused. After being released from Sherry's control, Plue immediately apologizes to Lucy and returns to the Celestial Spirit World.

Loke arc
After arguing with Loke, Lucy leaves with Happy and Plue and Plue 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
Lizardmen are attacking Erza and Lucy. Realizing that the Lizardmen only mimics the skills and abilities of their opponents, Lucy summons Plue, changing the Lizardman she is fighting to a similar size. Plue then starts to dance, gradually gaining speed. The Lizardman starts to mimic his moves, but is unable to keep up with Plue, and soon vanishes, defeated.

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

Major Battles

 * Lucy Heartfilia (owner) vs. Sherry Blendi
 * Erza Scarlet & Lucy Heartfilia (owner) vs. Daphne's Lizardmen

Trivia

 * Her quote when summoning him is: "Open a Gate of the Canis Minor! Nikora!".
 * Apparently, it was his idea for Natsu to make a team.
 * 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.
 * Mirajane believes that Plue is the strongest among all of the Celestial Spirits.
 * 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 gets very wrinkly in hot water.
 * Plue's character was featured in Hiro Mashima's previous work, Rave Master.
 * For Rave Master, Plue, who is created Hiro Mashima, is originally a doodle (unknown volume). It is interesting to note though, that it can be assumed Plue has been a Rave Master Guardian for all his creation time, even though it was never stated. Another note for the pronunciation of Plue's name, (in Hiro Mashima's notes - unknown volume) Plue is pronounced like the color, "Blue."