The immense army of the Alvarez Empire continues to press on the exhausted forces of Fairy Tail. With Makarov being at the end of his wits, Erza steps forward in an attempt to make a way to their guild, encouraging her allies as she takes down several enemy soldiers. Suddenly, everyone's attention is turned to a giant eye appearing above them: Irene searches for Mavis, who managed to flee from the enemy-controlled guild, however, the First Master decides to make a stand on her own, and with an illusion of her giant self, she raises everyone's morale, much to Irene's annoyance.
As a response to Mavis' act, the Scarlet Despair hits the ground with her staff, enchanting the empire's soldiers: transformed through Berserker, the entire army attacks Fairy Tail with a greatly increased power. After Makarov witnesses his kids' suffering, he realizes that there is only one thing left to do and gets into the stance for Fairy Law. Mavis rushes to him in an attempt to stop him, revealing the side effects of the spell, however, Makarov refuses to back down and unleashes the legendary Fairy Magic, using up the rest of his life force in the process. As the members of Makarov's guild weep his sacrifice, Irene reveals that his final act has taken out a majority of the army.
Meanwhile, Natsu and Gray are in the midst of a battle of their own, with Gray having found out his friend's true identity, as the Demon's power surfaced in front of him. They exchange multiple blows, until Erza appears between them to block powerful attacks of her friends. Tearfully, Erza questions their actions as the boys express their shock upon her appearance.
Seeing Erza's emotional state, both Natsu and Gray are reminded of her cruel past, as she lectures them on what it means to be a part of a guild, using Makarov's words. Erza then embraces them, expressing her love for the two, which finally calms them down. As Juvia, Wendy and Lucy arrive to the scene, Natsu and Gray fall down exhausted, losing any will to fight. Along with Happy and Carla, the group decides to head to Porlyusica, however, Erza notices someone's presence and warns her friends to take cover, just as Irene appears, causing a huge explosion. She greets Erza mysteriously and Wendy notices an obvious resemblance between the two.
Confused by her opponent's words, Erza orders the rest of her group to take Natsu and Gray away to safety, as she intends to find out the true meaning of Irene's statement and rushes at the woman in front of her. The Spriggan, now under the handicap of Larcade's Pleasure, attempts to counter-attack, but her spell is negated by Wendy's own Enchantment, who steps in to assist Erza.
With Larcade's Magic now gone, the battle continues in full force. Erza takes advantage of her superior swordsmanship skills and continuously attacks Irene, supported by Wendy from behind. As Irene finds an opening to cause a huge explosion in order to stop Erza's barrage of attacks, the Titania appears unscathed and launches numerous blades towards Irene in her Heaven's Wheel Armor. Wendy's hopes that it's over are soon dismissed as Irene has effortlessly evaded all the swords and even rearranged them into the shape of a flower on the ground. While Wendy expresses her shock at how ineffective Erza's attack was, Irene voices her disappointment about the same, melting the array of swords into the ground. As Erza once more questions her opponent's identity, Irene finally reveals herself as Erza's mother and the former Queen of Dragons. Even though Erza expresses her disinterest, claiming Makarov and the guild to be her true family, Irene proceeds to reveal her story from 400 years ago, and her connection to the Dragon King Festival, as well as the truth behind the creation of the Dragon Slayer Magic.
As Irene finishes telling Erza the aftermath of the story - Irene's suffering, Erza's birth and her attempt to possess her daughter's body, Erza thanks her mother for bringing her into this world, but also offers her thanks for throwing her away, which caused Erza to meet Fairy Tail. She requips into Rabbit Armor, once more ready for the battle. Claiming that her feelings haven't changed even though her own daughter stands before her, Irene causes yet another explosion that Erza easily evades. The latter then appears right in front of Irene and clashes with her, with the Spriggan smirking that such power is nothing against her. However, Wendy strikes from the side, hitting Irene with Sky Dragon's Wing Attack. Distracted, Irene lets herself open, allowing Erza to perform an attack with her Red-Black Twin Blades.
Wendy then expresses her pity about Irene's past, but states that there's no forgiveness for someone that doesn't love their own child. Irene changes her focus the little Dragon Slayer, pointing out that she also possesses the Dragon Seed, to which Wendy responds that it has been supressed by her mother, Grandeeney, so that she wouldn't transform into a Dragon. This information enrages Irene as she did not know that there was a way to stop the transformation into a Dragon and attacks the two female Mages, yelling out that she wants her life back. Wendy enchants Erza with Deus Eques and even negates Irene's countermeasure, which allows Erza to approach Irene and strike the Spriggan with both her swords joined together. However, as she is bleeding, Irene smirks and reveals the truth about Enchantments that she has realized - there must be a certain compatibility if one's personality is to be enchanted into another's body, and enters herself into Wendy - a Dragon Slayer and an Enchantress that fulfills these conditions.
Shocked to see a new personality in Wendy's body, Erza questions the whereabouts of the little Dragon Slayer, to which Irene replies that Wendy isn't anywhere now. Refusing to believe that, Erza charges at Irene, but is struck back by her kick. Irene then proceeds to test her Magic and covers Erza in an explosion, surprised that it's bigger than she had previously thought. Afterwards, she gives a test to Sky Dragon Slayer Magic, further attacking Erza. Irene expresses her joy to be in a new body, having started a new life and expresses her desire to erase her own daughter, while Erza continues to call out to Wendy. Unable to strike her friend's body, Erza continues to be pushed back by Irene until the Spriggan inserts and explosive Enchantment into the Mage's armor and causes it to blow up.
However, much to her surprise, the damage to Erza turns out to be insignificant, as Wendy, now in Irene's old body, has enchanted her with Deus Corona in order to protect her. While both parties express their shock that Wendy is capable of such feat, the little Dragon Slayer takes advantage of Irene's former Magic power and launches an attack towards Irene, following it by Deus Zero in order to get her body back. However, as she is being pushed back, Irene begins injuring Wendy's body more and more, asking her whether she still wants to come back to such a state, but Wendy does not hesitate, claiming that it's the body that contains her precious memories and completes the transfer. As she is slowly losing consciousness, Wendy, now back in her original body, asks Erza whether she can count on her to finish this, which Erza confirms and stands against an enraged Irene in her Clear Heart Clothing attire.
As Erza promises to Wendy that she will settle this soon, Irene asks whether she can really do that against a 400 years old being and aims an explosive Enchantment at Erza. Titania emerges from it, but Irene creates rays of energy that shoot towards Erza, something which the Queen of Fairies continuously evades. Irene expresses her disgust with Erza, claiming that even though she had protected her for 400 years, Erza still insists to interfere with the Spriggan's happiness.
Even though Erza states that she understands her mother's pain, she claims that she cannot lose as she slashes Irene with her sword. Landing in a few more strikes, Erza reveals that she knows a bit about misery herself, but points out her loved ones as her salvation. Unable to take this in, Irene punches Erza back as she begins her transformation into a Dragon. With another strike of the Dragon's claw, Erza finds herself on the ground, realizing that her bones are broken. Exclaiming that Erza can no longer move, Irene begins to prove that in her Dragon form, her Enchantments are of even higher power: she casts Deus Sema, and a horrified Erza watches as a meteorite nears their location from the outer space. She recognizes this spell to be a higher level of Jellal's Magic and immediately realizes that this will mean the death of everyone on the battlefield.
Refusing to give up, Erza makes use of her only working hand and propels herself into the air, with Irene commenting on this action as foolish. However, Erza calls back to the time everyone used to call her Titania, the Queen of the Fairies and exclaims that a queen protects everyone, and thus she shall do exactly so. With a sword in her hand, Erza charges at the incoming meteorite, as Irene watches in awe.
With a single strike of her sword, Erza annihilates the heavenly body which breaks into numerous tiny pieces that fall on the battlefield. Erza herself continues to fall towards Irene, yelling out for her to prepare herself, however, the transformed Spriggan points out Erza's inability to hurt a Dragon. Much to her shock, this instantly changes as Wendy slowly gets up and enchants Erza's blade with the power to slay Dragons, allowing Erza to deliver a devastating blow which undoes Irene's transformation. Even though this act causes some injuries to Irene, the two Fairies are now on the ground, unable to move anymore. Irene makes use of their predicament and grabs Erza's sword, intending to finish things, but then she notices her daughter's smile.
She recalls a similar smile on a then-baby Erza's face and yells out at her daughter to stop it, something which Erza pays no attention to and propels herself to headbutt Irene, with the sword stabbing through her side in the process. After coughing up blood, Irene grabs the sword yet again, but this time stabs herself with it as she realizes that despite taking countless lives up till this point, she is unable to kill her own daughter.
A surprised Erza can do nothing, but ask why, as Irene reveals that she stopped trying to enchant herself into Erza's body; she couldn't do it because of her adorable smile and that was the reason she then threw her away. With Irene's final words being an expression of love towards her daughter, Erza lies on the ground, watching her mother pass away and bids her goodbye. Wendy then appears next to her and they both check their injuries. Erza comments on how sorrowful Irene's story was, but exclaims that Makarov will always be her only parent. This statement reminds Wendy of something, as she asks about Makarov's smell disappearing from the battlefield, and Erza can do nothing but hug her friend and promise her that she will be there for her.