Lily's a time traveler now
Ok so,
You know how Hermione was the 'brightest witch of her age'? Well she got the time turner because of this, and she wanted to take more classes. We hear Slughorn say Lily was the brightest witch of hers. I don't think it's too far fetched to say that Lily might have wanted to do the same thing, and therefore also got a time turner. Then, Snape would want to use it. In this, Severus and Lily start fighting or something, and accidentally time travel to their 7th year. They see Jily snogging, and are very much confused. Lily and James talk to them about it, and at one point Snape insults James. Older Lily gets mad at him, and younger Lily is just sitting there stunned to silence because I'm going to date James Potter. Older Lily is amused at this, but ignores it, because SNAPE INSULTED THE LOVE OF MY LIFE, so she almost hexes him, but James stops her. There could also be a point where Snape says something like "What did I do? I need to make sure I don't do that", or something like that, and Lily counters with something like"Nah, I don't like you, and besides if you didn't do what you did, I wouldn't date THE James Potter ". Idk how to go from there but Snape would be so mad hehehehehehehe.
-Emma