Just brilliant! I was amazed at how well you handled the technical side of this with Lily narrating from the afterlife, watching the past, present and future play out in various ways. You tied it all together so neatly and made it obvious what Lily would choose.
I also liked this portrayal of Lily. Usually she's a bit more saintly - all love and forgiveness. We see her rediscover herself and realize how selfish she'd been. She was a perfectly normal girl and young woman, trying out her power and using Severus to do it. She discovered through Harry that there was something worthwhile to the man (and boy). And in discovering it, she realized she would never have it, had never had it.