As much as I adore BWLaB & CoMT (and I have actually read them more than my pick here) I have to go with The Tea Series. Her Severus is as close to my perfect IC Severus as any other I've ever read. As miserly with his affections as he with his belongings. And her Harry, pleased that he is in a relationship with someone as incapable of saying I love You as he is, is just the right amount of emotionally damaged. It's a tough read and there are other Severus' I prefer to read like Jadzialove's and Schemingreader's but if I have to pick just one then it has to be The Tea Series. My chest hurts now. This was physically painful.