She might use her magic skills to shield Harry from physical harm. For example, she could cast protective spells like a strong shield charm when Harry is in danger from dark wizards. Also, she may use her authority in Hogwarts to keep him away from those who wish to harm him, like making sure he is not alone in dangerous areas of the school.
You could look for general friendship - based fanfiction about them. It could show how McGonagall helps Harry with his studies or how they work together to solve problems at Hogwarts.
One possible reason could be that she is under some sort of dark magic influence. Maybe a spell has been cast on her that makes her act out of character and abandon Harry.
There's also 'Snape and McGonagall: A Different Perspective'. This fanfic delves into a more complex relationship between them. It starts with a simple encounter and then builds on their shared experiences at Hogwarts, including their different views on teaching and protecting the students. It's a really engaging read.
Perhaps when Harry is wrongly accused of something, and McGonagall uses her influence and knowledge to prove his innocence. She stands up for him in front of the whole school or the wizarding authorities, which is a very significant moment of her protecting Harry.
I'm not sure specifically which 'Harry McGonagall lemon fanfictions' are good as such content often goes against the spirit of the original work and may also be inappropriate. However, if you're interested in well - written fanfictions about Harry Potter and McGonagall in a more appropriate context, you can check out platforms like Archive of Our Own and look for fictions that focus on their teacher - student relationship in a positive and platonic way.
Since 'lemon' fanfictions involve inappropriate content, I can't really promote or discuss their themes. But in general, non - inappropriate fanfiction themes about Harry and McGonagall could include things like McGonagall's influence on Harry's academic progress at Hogwarts.
I don't recommend seeking out 'lemon' fanfiction in general. It usually involves adult and inappropriate content. Instead, you could look for well - written, non - inappropriate fanfiction about Harry and McGonagall that focuses on their mentor - mentee relationship or their interactions within the Hogwarts setting.
The contrast between their characters. Snape is often seen as dark and brooding, while McGonagall is more strict but fair. Their relationship in fanfics can be a study in opposites attracting. It makes for some really engaging and unexpected storylines.
One great fanfic is 'The Unspoken Bond' which delves deep into their relationship during the early days at Hogwarts. It shows how they supported each other through tough times. Another is 'A Shared Legacy' that focuses on their cooperation in protecting Hogwarts. And 'In the Quiet Moments' which is more about their private conversations and the unsaid feelings between them.