this was such a sad book! i cried! PLEASE DO NOT READ FARTHER IF U HAVENT READ THE BOOK AND DONT WANT TO KNOW WHAT HAPPENS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! but anyway, i cant BELIEVE snape would do such a thing! i mean, i knew draco wouldnt. dumbledore gave his life up for harry! that spell he used to defend him, it drained away all his energy! and i just thought, dumbledores the only person voldemorts afraid of? well, now voldemort can take over the world, cuz now theres noone to stand in his way! oh my god this sux! and harrys not cuming back, right? so hogwarts will be a complete disaster! when snape walked up there i seriosly thought he wuz gonna take draco away and defend dumbledore! o god... please leave comments, i cant talk anymore, i have so many more thoughts to say, but........ bye I CANT BELIEVE DUMBLEDORE'S DEAD!!!!!!!!!!!!!
Actually it was pretty obvious what Snape was going to do from the very beginning of the book when he made the Unbreakable Vow. Also, throughout the novel he was trying to help Draco, and he met with the D.E.'s, so it was extremely obvious what was going to happen, it was hinted at throughout the entire series, this was just him fulfilling his destiny.