Hi, I just have to say tha tI`m dreadfully sorry the man is dead, and thatI hate Snape,but Iwill say my point og view at thismatter.
Ibelieve in Dumbledores dugdement (I wonder if I spelled that right.. ore that?) I think that Snape is still on the Orders side.
He is souch a important spy, that he`ll have to sacrefice to staythere. He is unbelieveble inportant to The Order. That is why he has to prove he`s words to Narcissa, when she`s begging him for help. Even though Snape don`t know who it is Draco is to kill (As Dumbledore says, none is really close to Voldemort, event though they belive they are, I don`t think Snape knows about the plan), he have to make the unbreakeble vow, enything else might loock to suspicious.
When Draco is at Slughornes party, and Snape talks to him at he`s office, it is cleare that he don`t know who Draco is in order to kill.
In the end of the boock, when the man who dies (won`t leave spoilers) is begging for his life, it is not really what Harry think he is. Se, he is not begging for he`s life, he`s begging Snape to kill him, so that he can stay in he`s possition as a spy. He is not on the dark side, as Harry think he is. But now, evrybody think he`s bad. argh! I hate hm though.... anyway, concider my theory, won`t you?