Redemption: Harry Potter

I've always been reading Harry Potter fanfiction, and a few days ago I suddenly wanted to try writing one myself. This is my first time writing this kind of story, so please forgive any shortcomings. Here is the actual synopsis: He gave his heart, only to be betrayed for the sake of a single pill. Disillusioned, he never expected to get a chance to be reborn. He arrives in the world of Harry Potter. "May I ask why you are following me so closely?" The black-robed professor spun around, his wand pointed straight at my chest. "I was just wondering if I might have the honor of talking with you for a while." My eyes met those black, star-like eyes. "Green represents hope and true love; silver represents perseverance and endurance. Severus Snape, you are so weak when it comes to feelings. What right do you have to call yourself a Slytherin? Slytherins stop at nothing. Slytherins are cunning and treacherous, but everything they do is for the sake of their goals. And you, Snape, who won't even try to feel anything, are a coward." "Spirit of darkness, I swear upon my soul: briefly link my soul with that of Severus Snape, and transfer half of my remaining life to Severus Snape, so that he may be brought back from the brink. So be it." "Severus, Veritaserum might taste better if you put it in tea." "It kept giving up the things it was meant to leave behind, while continually taking in new things. It seemed to be shedding the shadows of its past, little by little, and being reborn. This isn't abandonment. It's a choice." He uttered the words to me: "Avada Kedavra." Nine years later, they meet again. "Who are you?" "Sir, do we know each other?" "Yes, you love Lily. She is your sunshine. Your salvation. What am I, then?" "Am I still a threat to you? Shall we try Avada Kedavra one more time?" Through all the twists and turns of past and present lives, who is whose original sin, and who is whose salvation? Volume One has been revised and released, with nearly ten thousand new words added. The old chapters have also all been revised. I hope you'll be happy with it. Chapters marked [New] are new chapters. The heavily revised chapters differ greatly from the originals, so I hope you'll give them a look. Of course, it would be even better if you read them again. Blushing, Please leave comments. I'd love your advice. Update: Chapter 62 Here's a picture of the professor. The English below it is his classic monologue. I can teach you how to bottle fame, brew glory, and even put a stopper in death. But there is one condition: you aren't the sort of dimwitted fools I usually have to teach.