Lucy Heartfilia's Rescue from Mercurius

Lucy Heartfilia's Rescue from Mercurius is an event taking place in the Grand Magic Games arc in which Natsu Dragneel, Wendy Marvell, Happy, Carla, Pantherlily and Mirajane Strauss head to Mercurius to rescue Lucy Heartfilia who was arrested by the Fiore Army.

Prologue
After their talk with the dragon Zirconis, the Fairy Tail Mages in the dragon graveyard find themselves confronted by Arcadios and Yukino Aguria. Stating that they have a plan, Arcadios invites the Mages to come with him to Mercurius, with Yukino adding that their plan can be the key to defeating Zeref and Acnologia.

After seeing the Eclipse Machine that they intend to have a Celestial Spirit Mage open so as to travel back in time and defeat Zeref before he was immortal, the Mages are then surrounded by the army's forces as the Minister of Defence, Datong, approaches. Angry with Arcadios due to the potential dangers of changing history, Datong orders his arrest, as well as the arrests of Lucy and Yukino. Natsu's Magic is taken by the Eclipse Machine, preventing him from helping and ending in the girls being arrested. The rest of the Fairy Tail Mages are then ejected from the castle afterwards. Datong tells them that due to the King's love of Fairy Tail, if they win the Grand Magic Games, they will be allowed an audience with him, which they accept as currently their only way to save Lucy.

The group soon returns to their lodgings to discuss what to do about Lucy's capture. Natsu, restrained to a pillar, yells how they should go rescue Lucy right away. Knowing that they can't save Lucy and become public enemies, Makarov begins to wonder why Lucy was captured. As the group tries working out the reasoning of the kingdom, Natsu tries to leave the lodge to try save Lucy but is quickly stopped by Makarov. Makarov tells Natsu that though they won't barge in, they won't stand down and do nothing like cowards. The next day, at the games, Mavis asks if Makarov has thought his plan through. Makarov tells Mavis that since their chances of winning the Grand Magic Games are uncertain, Natsu and his team will set out to save Lucy under the cover of the Grand Magic Games.

Arrival and Rescue
At the place, a guard takes a captured Natsu and Wendy to his colleague who asks who they are, to which the guard replies they were trying to rescue Lucy. Upon being told to throw them in a cell, the guard begins to head into the palace with Natsu and Wendy but one guard points him to where the cells actually are. When inside, the guard turns out to be Mirajane using her Transformation Magic to sneak them into the palace.

Soon after, Natsu and co. find Lucy and Yukino in a cell. Natsu melts the bars to get the two out as they're surprised by everyone's arrival. Lucy is given new clothes while she plots how to get her keys back. Before they can act though, the floor beneath them opens as everyone falls into an underground trap. An image of Hisui E. Fiore appears, as she tells the Fairy Tail members they are in a place no criminal has ever escaped and tells them all to rot there for sneaking into the palace. Though initially unable to find a way to escape, Carla soon discovers a passage nearby which can be used. The Mages squeeze through the narrow exit one by one. Wendy exits first and notices a severely injured Arcadios in the distance.

Rushing to his side, the Mages are told by him to get out of the way as a large shadow approaches them from behind and attacks, which they narrowly manage to dodge. Another figure approaches Wendy as well, knocking her and the Mages into the air. Natsu questions who they are as nearby, a plant starts growing, from which a person emerges as two more figures enter. Arcadios recognizes the five people as an independent unit supporting the kingdom, the Garou Knights. Explaining that they're the reason Abyss Palace is inescapable, Arcadios hears the Knights proclamation of their attack.

Two of the group, Kamika and Cosmos are the first to attack as the rest subsequently join them. As each knight steps into the battle, the Mages find themselves hard-pressed to fight while defending Lucy and Yukino, who are unable to fight, at the same time. During the course of the battle, Cosmos summons a gigantic flower to swallow the rescue team. As they are sucked into the air, Mirajane, Pantherlily and Natsu manage to destroy the flower with a combined attack, creating a large explosion.

As a result, everyone ends up separated from most others and the various Mages are forced to fight all the knights separately. Despite their various difficulties in battle, the Mages overcome the Garou Knights. Delivering finishing blows, the Mages reunite and threaten the knights into giving them the way out.

Soon after, the team searches for a way out after having beaten the Garou Knights. While talking, Loke suggests that it was Arcadios' jade amulet which protected him as it can act as a talisman, causing Wendy to remember the Jade Dragon. Yukino also notes that the princess is named Hisui which means jade as well, with Lucy and Carla adding that they need to meet her and decide for themselves if Eclipse is right or not. As Natsu gets angry over the princess being the one who threw them in Abyss Palace, the door in front opens and Natsu rolls on the floor towards it, coming close to a person wearing a hood. Looking up, Natsu asks who they are. The hooded person begins crying, apologizing and asking for their strength. Others recognize her voice as she does so. Removing her hood, the figure reveals themselves as Lucy, greatly surprising everyone.

As she cries further, the other Mages nearby ask how it's possible that she looks like Lucy, since she's not Gemini and they aren't in Edolas. The Lucy in the robe asks them about the Eclipse gate, presuming they already know about its time travel mechanism, and tells them she's from the future, shocking them further. For a moment, Lucy stares at her future counterpart while Loke expresses surprise at the situation. As the Lucy from the future attempts to reveal information about the country's future, she suddenly collapses. Natsu and Wendy take a look at her while Happy and Pantherlily question the situation. As Lucy stares at the fainted girl, Mirajane approaches her, at which point she states that the situation is creepy, wondering why she came from the future. Picking up the unconscious girl, Natsu states they'll take her with them since they can't leave her behind. As they leave the castle, the Mages state they'll fire a signal to show that the rescue was successful, though they ended up with one more Lucy than they expected.

While attempting to escape, the team gets lost due to not having anticipated the grand scale of the castle. Natsu suggests clashing with soldiers to be quicker, though Carla points out that their injured members makes that impossible. Mirajane states that they also need to make a good impression at the Grand Magic games due to it being sponsored by the king, though Yukino notes their actions to have eliminated that possibility.

Meanwhile, Lucy sadly stares at her counterpart from the future as Loke tries and fails to comfort her. Suddenly, the Lucy from the future wakes up and asks where she is. Her memory comes back to her as well, allowing her to remember that after she escaped Hell Palace, they got captured again by the army since they came across Eclipse and were unable to use Magic. Wendy then asks why she came back from the future, to which she replies that it was to prevent the worst possible outcome. An extremely shocked Natsu questions the revelation, with several others wondering about it as well. As Wendy asks whether it could be related to the events in the Dragon Graveyard, Natsu takes weaponry and suggests fighting the dragons, much to the surprise of the others. Lucy wonders whether anyone will really believe what is said to happen, though Natsu claims they will since it's her who told them.

Carla recalls her vision and realizes Lucy wasn't singing, but rather, crying and screaming as the castle came down. Quickly, Carla asks the Lucy of the future what happened to them in the castle, which is answered by silence, to everyone's sadness. Stating that she didn't know how many days passed after that, the future Lucy explains that she came to the past after waking up and using the Eclipse, despite not knowing how, and arrived on July 4th. When asked why she only came to the recent past, she states that the machine was damaged.

The future Lucy then asks the group to head through the underground and meet Jellal, who she explained everything to and should be forming a strategy, claiming that she doesn't have one. As she states she just walked around town, she apologizes to the group. However, Natsu thanks her for the information and states that they'll protect the future. While running through the underground, the group encounters the army. Noticing that Yukino disappeared along with Arcadios, Mirajane leaves to find them, leaving the rest to battle the knights. While battling, Natsu knocks down several knights but is suddenly struck from behind by Magic. However, despite having been caught off guard, Natsu is unharmed, stating that such an attack wouldn't work against a Magic specialist such as himself.