Snapedom

Shouldn't your comments on this question take account of these lines from DH:

[Dumbledore] "How many men and women have you watched die?"

"Lately, only those whom I could not save," said Snape.

[Chapter Thirty-Three, The Prince’s Tale]

However Calvinist JKR's attitude to salvation, Christianity does recognise repentance and grants absolution.

This is a man who has changed. We aren't God, to evaluate that change properly, but shouldn't we give Snape credit for whatever that change involves? Goodness knows other people in the series did - and do - horrible things, and they get something like a free pass from many readers (starting with Dumbledore).

Fanfic is of course free to elaborate on both aspects of his actions as a DE, real or pretend. Snape's actions in canon in DH, however - especially in regard to protecting the students as far as he can, even when they do damn-fool things that must have him rolling his eyes, if not raising them to heaven in despair - suggest that he is prepared to take considerable risks, in a time of great peril, and lacking any support system, in pursuit of what he now believes, and has long believed, to be right.

Surely that persistence suggests that he will not, at the least, backslide?

/gets off moral high horse