Did Lily ever find out that Snape had changed sides?

Question

The decision to hide the Potters was done partly on the basis of the information that Snape passed to Dumbledore after he'd overheard Sybill Trelawney's prophecy.

"Hide them all, then," he croaked. "Keep her - them - safe. Please."
_{(Deathly Hallows, Chapter 33, The Prince's Tale).}

Later Snape makes Dumbeldore promise that he will never reveal his true feelings for Lily.

There was a long pause, and slowly Snape regained control of himself, mastered his own breathing. At last he said, "Very well. Very well. But never - never tell, Dumbledore! This must be between us! Swear it! I cannot bear...especially Potter's son...I want your word!"
"My word, Severus, that I shall not reveal the best of you?" Dumbledore sighed, looking down into Snape's ferocious, anguished face. "If you insist..."
_{(Deathly Hallows, Chapter 33, The Prince's Tale).}

However, that conversation happened after Lily was already dead. Do we have any way of knowing whether or not Lily knew the real reason why she and her family were to suddenly go into hiding? Was she told that the Fidelius Charm was being cast on the basis of Snape's information? Or did she go to her grave entirely unaware of Snape's continuing feelings for her and of Snape's true loyalties?

Answer 1

I don't believe that there is any canon specifics here, however, I also don't think that Dumbledore would have told anybody. Remember that Dumbledore agrees to protect them on the basis that Snape will become a spy for the original Order of the Phoenix. I can't imagine that he would have told very many people that Snape was spying for him; especially given how secretive Dumbledore was.

Answer 2

Probably not. Voldemort was a Legilimens, so telling her would likely have been too big a risk.

Even if Snape wanted Lily to know, he probably wouldn't be able to tell her. Lord Voldemort was a very skilled Legilimens, so he could read the thoughts of anyone who wasn't good enough in Occlumency. Dumbledore knew, but they would have been able to cover that up as him just doing a good job at fooling Dumbledore. We know that the Dark Lord being able to read people’s minds could possibly reveal Snape as a spy, since Dumbledore tells him to be careful Harry doesn’t know he’s the one giving him the Sword of Gryffindor, so the Dark Lord can’t see it in Harry’s mind.

“Good. Very good!’ cried the portrait of Dumbledore behind the Headmaster’s chair. ‘Now, Severus, the sword! Do not forget that it must be taken under conditions of need and valour – and he must not know that you give it! If Voldemort should read Harry’s mind and see you acting for him –”
_{^{- Harry Potter and the Deathly Hallows, Chapter 33 (The Prince’s Tale)}}

Unless Lily was a very skilled Occlumens at the same level as Snape, which is known to be a quite rare talent, telling her would have put Snape at risk of being discovered as a double agent. Lord Voldemort would only have to read Lily's thoughts to find out Snape's true loyalty. The intention was for Lily to stay alive, so they would have had to prevent the Dark Lord from reading her thoughts until his defeat or her death.

Even the way that things happened, the Dark Lord spent a long enough time talking to Lily to convince her to step aside that he could have read her mind before he killed her. He wouldn't have been able to do anything about it at that point, but once he regained his power, he would have known not to trust Snape.

Answer 3

The Potters went into hiding because Dumbledore "knew" (was quite sure) that Snape brought the prophecy to Voldemort. Whether Snape later changes sides is irrelevant, Voldemort already received the information about the prophecy, and the fact the Voldemort knows about the prophecy, together with the fact that later Harry is born at the end of July, is reason enough to protect the Potters (and the Longbottoms).

So I think that the assumption that the decision to hide the Potters was done partly on the basis of the information that Snape passed to Dumbledore is wrong, I think Dumbledore had reason enough to protect them before Snape came to him.

Snape may have told Dumbledore to "Hide them all, then". But it doesn't take someone as intelligent as Dumbledore to find out that Voldemort would try to eliminate a potential danger, so the Potters would be already hiding and there would be no need to tell them that it has anything to do with Snape switching sides, because it likely happened even before Snape switched sides.

Snape wants Dumbledore to protect the Potters, but he would do that regardless of Snape. The Potters are members of the order, and if Harry is the one mentioned in the prophecy, he would not want to lose him.

As Dumbledore is generally secretive and Snape has explicitly demanded that Dumbledore didn't tell anyone, it is likely that Dumbledore didn't tell Lily.

Answer 4

Lilly became more distant from Snape when they became adults. They were in separate houses and, as was mentioned, the Potters were in the Order of the Phoenix and Snape was a Death Eater. Only when he learns that her son is suspected to be the Chosen One does Snape beg for their protection, on the condition that Dumbledore won't reveal who he really is. So, no, I doubt she knew how deeply Snape felt in retrospect.