Perhaps the OC has a special ability that is causing problems for them, like attracting dark spirits. Mirajane, with her experience in dealing with various magic - related issues, tries to help the OC control this power. As they spend more time together, they form a deep bond. And through their adventures together in the Fairy Tail world, they fall in love and face challenges side by side.
One idea could be that the OC is a new member of the Fairy Tail guild. Mirajane takes the OC under her wing as a sort of mentor. They could go on a mission together where they have to face a powerful dark magic user. Along the way, the OC discovers a hidden power within themselves with Mirajane's help and encouragement.
Another plot could involve the OC being from a rival guild initially. But after getting to know Mirajane during a guild - to - guild competition, they start to question their loyalty to their own guild. Mirajane and the OC develop a friendship that gradually turns into something more. They then have to deal with the consequences of falling for someone from a different guild.
One popular 'oc x mirajane' fanfiction might be those where the OC is a new mage in the Fairy Tail guild and gradually forms a deep bond with Mirajane. They could start as friends, and through various adventures together, like fighting against dark guilds or solving mysteries in Fiore, their relationship evolves into something more romantic.
Maybe an OC who has the ability to communicate with spirits. In the 'fairy tail x oc fanfiction', this OC could discover that there are ancient and powerful spirits that are about to be awakened due to some dark magic ritual. The OC tries to enlist the help of the Fairy Tail guild to stop this from happening. Along the way, they face many challenges and also have to deal with the guild's initial skepticism about their powers and the existence of these spirits.
One idea could be a story where they go on a quest together. Maybe they have to find a rare magical item. Natsu's impulsiveness, Mirajane's charm, and Erza's strict leadership combine in interesting ways during the adventure.
One idea could be that the OC is a new member of the guild and Mirajane takes them under her wing. They could go on adventures together and the OC slowly discovers Mirajane's past and they form a deep bond. Another plot could be a love - hate relationship at first. The OC might misjudge Mirajane, but as they get to know each other better, they fall in love.
One idea could be that Mirajane and Natsu get lost in a mysterious magical realm during a mission. They have to rely on each other's skills and knowledge to find their way back. Natsu's brute strength and Mirajane's transformation abilities would be useful in different situations as they face various magical creatures and obstacles.
Well, a great plot could be that the OC is on a quest to find a rare magical item. Irene, initially an obstacle, realizes the OC's pure intentions and decides to help. Along the way, they face many challenges that force them to rely on each other, and love blossoms. Or perhaps the OC is a singer whose music has a strange effect on Irene. She is drawn to the OC, and they start collaborating. As they do, they discover they have a deep connection. Also, the OC could be a time - traveler who accidentally lands in Irene's time. Irene, intrigued by this strange person from the future, becomes friends with the OC and eventually love develops as they learn about each other's worlds.
One idea could be that the OC has a special power that Mavis senses and they form a connection through it. For example, if the OC can communicate with ancient spirits and Mavis, being an ancient and powerful mage, is intrigued by this ability. They could then embark on a journey to discover more about the origin of this power and in the process, develop a deep friendship or more.
Another idea is that the OC is from a different land and has a completely different view of magic compared to the people in the Fairy Tail world. Hisui, as someone interested in different cultures and magics, is intrigued by the OC. They start a journey to understand each other's worlds better. During this journey, they encounter various magical creatures and have to overcome cultural misunderstandings and the opposition of some who don't like the idea of mixing different magics.
One plot idea could be that the OC and Karen meet during a dangerous mission. The OC, with their unique abilities, saves Karen from a powerful enemy. This event sparks a connection between them, and they start to train together to become stronger. As they train, they learn more about each other's pasts and dreams, gradually falling in love.
Well, a great plot could be that the OC is a former enemy who has a change of heart. He was once part of a dark guild but realizes the error of his ways. Lucy is the first to see the potential for good in him. They start training together, and the OC discovers he has a special connection to Lucy's celestial spirits. Maybe he can communicate with them in a way that Lucy can't. This leads to them uncovering a mystery about the origin of celestial spirits. Another option is that the OC has the power to create portals to different dimensions. He accidentally pulls Lucy into a dangerous dimension. They have to rely on each other to find their way back, and in the process, their relationship blossoms.