At no point in the books is there any suggestion that Snape does anything but put a recipe on the board, stalk around spooking the non-Slytherin students while they try to follow it, and set essays between classes. Anything they learn of potions is from the books, on their own time, in spite of him, as far as I can see. Fics that try to make him better usually take it too far the other way, as the mountains of horrible Alan-Rickman-husbando-squee trash will attest.
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‎noli esse culus
‎noli esse culus