All the ppl who haven’t read Harry Potter and Half Blood Prince are not advised to read further

i guess Snape is still with d’dore coz of 4 reasons which i can remember

1. In the beginning, when he was at the house, there was wormtail (peter pettigrew). I mean, u can’t expect any of the order of the phoenix members or atleast d’dore himself sometimes dropping into his house… tht means, this is done with d’dore’s knowledge. Moreover he had the unbreakable vow with Narcissa, which he had to keep…

2. In the end, remember d’dore begging to snape.we don’t know the meaning of that begging. we r jst guessing it is to save him. But I should say killing him then was the most sensible thing snape did . Else Malfoy would have been killed, so would have been he. In that way, he was able to keep his undercover identity not revealed

3. After HBP, we know snape is one of the most brilliant wizards alive, apart from voldemort. And we should believe tht rowling is not dumb enough to make Harry a super hero who can kill v’mort by himself. He needs a very powerful guy to help him. It could be none other than snape, as it will be something that v’mort hasn’t ever dreamt of. that will be a big blow for him..

4. Moreover, snape tells in the beginning tht voldemort is satisfied abt him and his actions, he explains in detail to bellatrix (Narcissa’s sister). And mind u, he has an emotionless face, which can trick anyone…

This was the mail which I sent to my sis anagha… n i’m adding her reply also…..

“w/e u sed wuz completely rt….i tot dt eitha snape n malfoy(or both) ll join hands wid hp. snape iz reeely gd at makin xcusz, n all dt stuff wuz probably 2 convince ynw(u-noe-hu) n d’dor izn soo dam dum 2 b wiv snape if he dint av a reezon, he sed he did…it cud b netin…snape killd d’dor cuz he had 2….bt he probably mde planz 2 help harry l8r…mus b noza ting 4 ynw 2 gt foold….
so i dun reely tink snpe iz evil…n der az 2 b som1 reeely gd 2 help harry wiv da horcruxz nw dt ddor iz ded…so it ll b snape most probably….bt bellatrix iz nt sooo bad nw dt u tink abt it….so u neva noe…it cud b ne1″