One plotline could be centered around a powerful wizard or witch who is trying to create a new form of life using a magical egg. But instead of the expected outcome, the egg somehow causes a mpreg situation for a character involved in the experiment. Another possibility is that there is a magical artifact in the form of an egg that has been lost for centuries. When it is found, it has a strange power that causes a character to experience egg mpreg. The story could then follow how the character copes with this new and unexpected situation, and how it affects their relationships with other characters in the 'Harry Potter' world.
Another plotline might be that a centaur discovers they are pregnant as a result of some ancient magic being reawakened. The centaur then has to navigate their own traditional beliefs and values about pregnancy and family, while also dealing with the potential implications for the centaur - human relations in the Harry Potter world. They might seek help from certain characters in the wizarding world, like Hagrid, who has a connection to magical creatures, and together they try to figure out how to handle this unprecedented situation.
One possible plotline could be that a powerful magical spell in the Harry Potter universe somehow crosses over and affects Tony Stark, causing the mpreg situation. Then, the story could revolve around Tony trying to figure out what happened and how to reverse it, with Harry Potter characters helping or hindering him. Another plotline might be that a new form of technology in Tony Stark's world has an unexpected side effect when combined with the magic of Harry Potter's world, leading to the mpreg. And the characters have to find a way to deal with the social and magical/technological implications.
I'm not aware of any specifically popular 'Harry Potter' egg mpreg fanfiction. Fanfiction often covers a wide range of themes, but this one seems rather unusual and might not be mainstream. However, the 'Harry Potter' fandom is vast, and there could be some niche works out there that deal with such a concept.
One possible plotline could be that while Snape is mentoring Harry, some dark magic incident occurs that results in Harry's unexpected mpreg situation. Snape then has to not only continue mentoring Harry in magic but also deal with this strange and difficult situation, perhaps protecting Harry from those who would judge or harm him because of it.
One possible plotline could be that through some magical - technological mishap, Tony Stark ends up in the Harry Potter universe and somehow becomes pregnant. Maybe he has to deal with the magical world's reaction to this very un - magical situation while also trying to find a way back to his own world. Another could be that a spell or some new technology allows for a cross - universe connection that results in the mpreg situation, and then it's about how the two characters from different worlds navigate this new reality together.
In some stories, the reason for Snape helping Harry could be related to a prophecy or some long - hidden magic. The plot could involve Snape gradually changing his view of Harry as he helps him through the mpreg. They might develop an unexpected bond during this time, and together they face challenges from other characters who either don't understand or oppose what's happening to Harry.
One possible plotline could be that Harry discovers he is in this unexpected mpreg situation and is initially terrified and confused. Snape, despite their past differences, steps in to help because he realizes Harry has no one else to turn to. Snape could use his knowledge of potions to ease Harry's physical discomfort during the pregnancy.
One possible plotline could be about the Weasley family trying to improve their financial situation. Maybe they come up with a new business idea in the wizarding world, like a magical product that becomes a huge success and changes their economic status. Another could be a story about how the Ministry of Magic regulates the financial system in the wizarding world, and there are some characters who try to manipulate or reform it.
Well, one possible plotline could be a story where a character from the wizarding world, perhaps a powerful wizard, takes on a concubine in a parallel world or an alternate version of the wizarding society. The concubine might be from a different magical culture and their relationship could cause political or social unrest within the wizarding community.
One possible plotline could be that the parrot is a magical pet of a new character who enters Hogwarts. This parrot has the ability to detect dark magic, so it helps the students in their fight against the forces of Voldemort.