So this is a feature that's bugged me for a while as I really wanted to explore the concept of a Muggleborn in Slytherin, given the history of the house. As it stands, if you choose to be a Muggleborn, you are immediately prevented from achieving Slytherin house, even if you answer all the cunning and ambitious answers.
No where in Harry Potter lore does it say Muggleborns cannot be Slytherin and in modern times, the community has become more accepting of Muggles as a whole with more and more half bloods appearing, so why not Muggleborn? Adding to that, the house is chosen by your values, not your blood status. Families often end up in the same house but Sirius Black is proof of that not always being the case.
I think for the openness and future timeline that World of Potter represents, Slytherin should be able to accept Muggleborns. Their ambition and cunning nature could be stronger than their blood. Besides, imagine the potential for a writer in that scenario? And aren't we all here to open up a world of exploration in our writing and our stories?
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