Love Potion from Travalya Ra was my first Snack story, which hooked me into that pairing definitely.
Besides the obvious reason of falling in love with the boyz it was the fackt, that in Snack Harry still has the possibility to remain to be just a teenager having Ron and Hermione as his friends. In opposite to Snarry, where in the first place Harry has to keep a secret, which sooner or later will drive him away from his friends. At last temporarily.
No, don't understand me wrong. I love Snarry. It is my second favourite pairing and it remains so mostly because of Snape. I just wanted to tell this above :-).
Well I would like to know, what brought you liking Sirius/Snape in the first place?