The shady guy at school should be involved with the story of the woman in the pharmacy. At the very beginning, when you try to find out about anal, she wont talk to you about it but your friend at school then tells you, that the shady guy sells pills that will help you, which you then put into her drink during her coffee break. So, it is not Adriana who sends you to him, but the guy at school.
which guy at school....???. I have done the anal thing I have progressed into the story very far (450 days) and still cant get the shady guy to speak to me.