Drunk Lucy could also be very argumentative. She might start debates with the more serious guild members like Erza about the silliest things, like whether or not it's proper to eat cake with a fork or hands. This would lead to some comical exchanges as the other members watch in amusement.
Happy would be flying around, providing support. He could carry small items or messages between the other Fairy Tail members. And he might even try to use his fish - shaped Exceed Beam to blind Godzilla or at least annoy it a bit. Wendy could use her Sky Dragon Slayer magic to heal any of her comrades who got injured during the fight with Godzilla. She might also try to use her magic to weaken Godzilla's attacks by creating gusts of wind to blow them off course.
Some of the more mischievous guild members like Gray might tease them a lot. He'd probably make jokes about it every chance he gets, much to Natsu and Lucy's annoyance. Happy, on the other hand, might be really confused at first but then start to see it as a sign of their closeness and be really happy for them.
There could be a void in the guild's social dynamic. Lucy is often involved in the guild's daily activities and socializing. Without her around, the guild might seem a bit quieter and less lively. The other members would have to adjust to her absence, and this could lead to some changes in the relationships within the guild.
The guild as a whole would likely mobilize. Erza would start formulating a strategic plan. She'd consider the strengths and weaknesses of Acnologia and figure out the best way to approach the situation. Gray would also be ready to fight, using his ice - make magic to support the rescue mission. They would all be united in their determination to get Lucy back safely.
In some fanfiction, Bickslow teases Lucy a lot, which is his way of showing he likes her presence. He might make fun of her in a light - hearted way about how she gets flustered around Natsu.
She would fit in very well. The Fairy Tail guild is all about family and acceptance. Given her parents are Lucy and Natsu, she'd be welcomed with open arms. She could learn from the older members like Makarov and Mirajane, and bond with the younger ones like Romeo. Her magic skills would also contribute to the guild's strength during battles or when helping the town.
Natsu would be a very likely character. Since he and Lucy are close friends in the original story, if Lucy travels back in time, Natsu might be one of the first people she seeks out. They could have adventures together in the past, with Natsu being his usual impulsive self and Lucy having to keep him in check with her knowledge of the future.
Naruto would probably be very enthusiastic and friendly towards Lucy right away. He might be curious about her celestial spirit keys and ask a lot of questions. Lucy, on the other hand, might be a bit more cautious at first but would be drawn to Naruto's positive energy.
The guild would likely be ecstatic. Gray would probably make some snarky comment about Natsu finally growing up, but deep down he'd be happy for his friend. Erza would be all for it and might start planning the wedding immediately, giving orders to everyone in the guild to help out.
Her relationship with Natsu would likely change. Natsu might be initially distrustful of Lucy if he senses her connection to End, since End is often seen as an enemy. But then as he realizes that Lucy is still the same person deep down, their bond could become even stronger as he helps her control this new aspect of herself.