A possible plot is that Minerva McGonagall, during a magical experiment gone wrong, creates a time - loop situation where she is constantly surrounded by a harem of her past students (now grown - up) who have come back to Hogwarts for different reasons. She has to manage this chaotic situation while also trying to fix the time - loop.
Perhaps there could be a plot where a powerful dark magic affects the Hogwarts staff, and as a result, Minerva McGonagall ends up with a harem of wizards and witches who are magically bound to her for protection. This situation forces her to not only deal with the unexpected company but also find a way to break the spell without harming anyone.
One interesting plotline could be McGonagall mentoring a young and troubled student. It would show her nurturing side, which we don't always see in the original books. Another could be her taking on a special mission during the war, like protecting a secret magical artifact. This would highlight her bravery and loyalty to the wizarding world.
Another plotline might involve a time - travel scenario where Harry Potter and Minerva McGonagall have to work together to change an event in the past that is threatening the future of the wizarding world. This could lead to some really cool interactions as they navigate through different eras.
Some characters in the harem might be developed as admirers of McGonagall's strict yet fair teaching style. They could be shown as constantly trying to impress her with their magical skills, like a young wizard who practices transfiguration just to get her attention.
One interesting fanfiction could be about Minerva McGonagall's early days as a teacher and how she interacted with a young Harry Potter. It might show her guiding him in secret before he even knew he was a wizard.
There might be a fanfic that focuses on Minerva McGonagall's backstory in relation to Harry Potter. For example, it could explore her thoughts and feelings when she first saw Harry as a baby, knowing the prophecy. It could also show how she secretly protected him during his early years at Hogwarts, before he even knew about the danger he was in.
One idea could be a story where Minerva and Severus have to team up to protect Hogwarts during a new, unexpected threat. Maybe a dark magic artifact is discovered near the school and they must use their combined knowledge and skills to keep it from falling into the wrong hands.
How about a story where Hermione discovers a hidden talent for transfiguration that even McGonagall is surprised by. They then work together to perfect this new form of transfiguration, but face opposition from some of the more traditional - minded professors. Or, in a post - war Hogwarts, they collaborate to reform the curriculum to include more practical and modern magic, all while dealing with the after - effects of the war on the students and the school.
In some fanfictions, Minerva adopts Harry after realizing the Dursleys are mistreating him. She then takes on the role of a mother figure, which is a huge change for Harry. This could include her taking him shopping for new robes and school supplies in a more loving and nurturing way than the Dursleys ever did. She might also introduce him to the wizarding world in a more personal and gentle way, making him feel truly welcome.
One common plotline is McGonagall protecting Harry from the Ministry of Magic when they wrongly suspect him of something. For instance, if the Ministry believes Harry is using Dark Magic, McGonagall stands up for him, using her influence and knowledge of Harry's character to prove his innocence.
One plot idea could be how she manages her pregnancy while still fulfilling her duties at Hogwarts. Maybe she has to keep it a secret at first and enlists the help of a few trusted colleagues like Dumbledore. Another could be exploring her relationship with the father, whether it's a fellow wizard or a Muggle, and how that relationship evolves during the pregnancy.