Lucy Heartfilia joins Fairy Tail

Lucy Heartfilia joins Fairy Tail is an event that takes place during the Macao arc.

Prologue
After an incident in Hargeon Town, which involves a known man impersonating Fairy Tail Mage Salamander, Rune Knights are called to the town to take care of the situation. A known participant, Lucy Heartfilia, escapes from them with the her new friends Natsu and Happy; surprisingly, Natsu is revealed to be the true Salamander of Fairy Tail. He offers to invite Lucy to join his and Happy's Guild, Fairy Tail, and Lucy excitedly accepts.

Entrance to the Guild
Shortly after fleeing Hargeon Town, Natsu, Lucy and Happy arrive at the Fairy Tail Guild Building in Magnolia Town. Lucy is amazed by the size of the building and is welcomed to it by Happy. Afterwards, the three head inside.

Natsu loudly announces his arrival, then proceeds to kick one of his guildmates on their faces, angered that the information he got about Igneel being in Hargeon Town was a lie. He then starts to rampage in the building causing the others to try and restrain him, though in the end they also get caught up in the fight. Lucy meets several of the Guild members and is shocked by how eccentric they are. In addition, she speaks to Mirajane who tells her that the antics occurring within the Guild makes it a fun place. The battle starts to get serious until their Guild Master, Makarov Dreyar, stops it. He yells at the Guild while also employing his Titan Magic, terrifying Lucy, though when he returns to his normal self Lucy remains shocked.

Makarov shows papers sent from the Magic Council and lists all damages done by the members, scolding the responsible Mages for their actions. He says that their actions have made the Council grow more restless with him but states that he doesn't care what they think; Mages wouldn't be able to develop their Magic if a higher authority intimidates them into not using it to its full potential. Therefore, he and the Guild should not care. As Mages of Fairy Tail, they should follow what they believe in.

Later that night, Lucy is given a pink Guild Stamp on her left hand, making her an official Mage of Fairy Tail.

Aftermath
Shortly after, Makarov speaks to a young boy named Romeo about his father still being away on a Job at Mt. Hakobe. He assures Romeo that Macao will be fine. However, Natsu, who overheard the conversation, decides to go to Mt. Hakobe and personally rescue Romeo's father, Macao. Mirajane theorizes that he's doing so because he sees himself in Romeo and explains to Lucy about Igneel, Natsu's foster parent.

Later on, Lucy joins Natsu and Happy to Mount Hakobe.