Arcadios

Arcadios is a Squadron Chief in the Royal Kingdom of Fiore, though he seems to also have an allegiance towards Zeref.

Appearance
Arcadios is a well-built man of average height, seen to be wearing armor of the Cherry Blossom Holy Knight Squadron. He has deep set eyes and high cheekbones, with a small scar running from his left temple to the edge of his thick eyebrows. He also has a snub, square-shaped nose. His hair is dark and wavy, sticking up around his head, with prominent sideburns that join into a curved and pointed beard.

Personality
Arcadios seems to have a dark personality, and has a tendency to use metaphors while talking. Also, as he seems to be affiliated with Zeref (whom he called "Lord") he doesn't come across as a person with good intentions. Arcadios is also a person who is willing to sacrifice the lives of others in order to achieve his goals.

Grand Magic Games arc
As Arcadios watches the fight between Lucy Heartfilia and Flare Corona, he gets excited that "it" will be completed at the Grand Magic Games this year, and wishes for Zeref to wait just a little longer.

After the first day of the Grand Magic Games, Arcadios is seen kneeling in the presence of Fiore's King, asking him if he has any requests for the battle pairings of the second day. After hearing the King's broken reply and request that he rest, Arcadios leaves the room, laughing to himself at the thought of being able to relax when "that" is almost complete.

During the second day of the Games, Arcadios accompanies the King to Domus Flau to view the battles portion of the competition. After the King conveys his excitement at getting to see Erza Scarlet fight Bacchus, Arcadios quickly realizes that he has misinterpreted the King's request from the day before and organized for Elfman Strauss to fight Bacchus instead. When the King expresses his annoyance at the mix-up, Arcadios begrudgingly apologizes. During the battle, Arcadios has ordered some men to kidnap Lucy. However, the men fail and are captured by Natsu Dragneel, angering Arcadios and prompting him to proceed to plan B, a plan to utilize the discord between Fairy Tail and Raven Tail in order to capture Lucy and fulfill his Eclipse Plan.

Arcadios is later approached by the Minister of Defense, Datong, who questions him about his intention when he tried to have Lucy kidnapped. Arcadios tells him that he needs Lucy to try a test run of the Eclipse plan, revealing to him that it is already complete. He also tells him that he is willing to sacrifice her life in order to open the gate for changing the world, much to the Minister's horror.

Upon seeing Yukino Aguria battle Kagura Mikazuchi in the last battle of the second day, Arcadios displays his amazement that there is another Celestial Spirit Mage in the tournament, happily grinning as he confirms that his plans are now more assured than ever before. After the second day finishes, Arcadios is seen rifling through a mass of papers and books, figuring out that with Lucy and Yukino's keys combined, the Twelve Zodiac are complete. After stating that the Eclipse Plan will now activate completely, he begins to laugh maniacally and call Zeref's name.

At the end of the Fourth Day's Event, Naval Battle, Lucy Heartfilia, one of the competitors, is drastically-brutalized by Minerva before her defeat in the event. Arcadios, afraid of losing his targeted Celestial Spirit Mage, sends his guards and orders Mato to stop the event immediately.

After Lucy is brought to the infirmary, Arcadios is seen talking with Datong about it, saying that their strategy failed and the best thing to do would be enjoy the rest of the festival. Arcadios says that the plan that will change the world will start in 3 days, much to Datong's tension. He then states that Zeref has been waiting for it.

On the night of the fourth day of the Grand Magic Games, Arcadios and Yukino travel together to the catacombs underneath the Domus Flau, where they encounter Natsu, Lucy, Wendy, Gajeel, Gray, Happy and Carla trying to resurrect a dragon soul from the dragon skeletons that litter the caverns. Having not been seen by the group, he and Yukino stand back and watch as Wendy successfully uses Milky Way to summon forth Zirconis, a huge emerald dragon. He listens in as Zirconis explains the history of the dragons to the group, as well as Acnologia's past of once being human, and the destruction of the dragons at the hands of the Dragon Slayers. When Zirconis fades away, Natsu and the other Dragon Slayers begin to wonder if overusing their Magic will turn them into dragons as well, and Arcadios uses this moment to reveal himself, stating that something like that will not happen and that his research into the history of the dragons has now been confirmed. Ignoring the surprised reactions of the Fairy Tail Mages, Arcadios goes on to ask if they have heard of Zeref's dark book of Magic, and states that he believes it was Zeref who turned Acnologia from a human into a dragon. From this, he concludes to the group that destroying Zeref, the root of all darkness, is the first major step to defeating Acnologia.

Arcadios introduces himself to the Fairy Tail Mages and briefly explains that, in part of his plan, he needs a Celestial Spirit Mage. Natsu approaches him with hostility, wondering why the need for Celestial Spirit Mages is so important. Arcadios does not answer his question and instead instructs the small group to follow him. He leads them inside Mercurius. There, Arcadios reveals that he staged the attempted kidnapping on Lucy several days before, and apologizes for his actions. As he leads the Mages further inside the building, Arcadios elaborates more on his plan: the Eclipse Plan. He adds that it is set to take affect in three days, on July 7; in addition to being the day of a solar eclipse, July 7 is also the day in which the Dragons disappeared fourteen years ago. Soon after, the group is approached and surrounded by a team of Fiore Guards led by Datong. Arcadios is shocked that Datong is betraying him, only to be told that the latter never agreed with his plan in the first place. Datong then issues that Arcadios be apprehended under suspicion of treason.

Soon after, a severely battered Arcadios is discovered underneath the castle in Abyss Palace by the Fairy Tail Mages who were sent there along with Yukino. As the Mages attempt to wake him up, he weakly tells them to get away as a large figure approaches from behind and attacks. As more figures approach and reveal themselves, Arcadios explains them to be an independent unit of the Kingdom known as the Garou Knights and states they're the reason why Abyss Palace is inescapable.

As Natsu laughs at the sight of the Garou Knights because of their looks, Arcadios warns him that they are efficient killers despite their appearance. Soon, the Mages are separated because of the impact of an attack, and Arcadios stays with Lucy, Yukino, Happy and Carla. When Uosuke appears in front of them, Lucy and the others are confident that he looks dumb and they can easily beat him, but Arcadios says that he is such a skilled assassin that not even the bones of his victims remain when he is done with them.