Found: Harry Potter works at an apothecary fic
Hello,
I am looking for a fic in which harry somehow end up in diagon alley and does some work at an apothecary. set before Hogwarts and harry has an aptitude for potions and goes by a different name. He meets Snape before going to Hogwarts and they get on well but Snape does not know who he really is. Once Harry is at Hogwarts Snape treats him that same way as he did in canon, because he does not know harry is the other kid.
I also think that they exchange some letters in which harry informs Snape that his potions teach is no good.
Thanks for any help!