Oh, oh! A LONG plotty story in which Cedric lives! *does jig of joy* Not sure who you are, or if you know me from adam, but when the reveals come, I plan to put this on my Cedric's recs page, if you don't mind. Also, choosing "Eric's Song" for the titles?! I loved it. I already associate that song with Cedric (albeit for different reasons and a different pairing, nonetheless) ... I'm not really familiar with Teddy in fanon, but I liked how you handled him here, and his desires as an orphan, which would be both similar to and different from Harry's. I also liked that you didn't run away from the consequences of time travel.
Someone above was asking for a sequel, and I, too, would be curious to see "what came next" if you had any interest in continuing. Does Teddy stay there? What other changes happen? Are there any consequences to him? DOES Lupin marry Tonks? I got a hint here of Sirius/Remus vibes, or I may just have read into it. But what would happen if Teddy isn't born in this time line? What would happen if he is? How will Cedric's father respond to his son's boyfriend? Lupin accepted it fairly easily, but Remus already lives with the consequences of social ostracism. What is the attitude of the wizarding world in general? Similar to larger Britain? More conservative? Amos seems very concerned with "appearances."
So yeah, not like I'm trying to tempt you or anything. ha! There's just not been a lot of fiction lately that features Cedric. Not surprisingly, perhaps, but I miss the boy. :-( So yeah. *lure, lure*
There are a number of smaller things I liked too. How Teddy seems to have a bit of a boy-crush on Cedric from the beginning that develops into more, despite what he knows. The easy use of British slang. Not sure if you ARE British, in which case that's a silly compliment (g), but there are loads of American/Canadian (other) writers in HP. I saw one "guys" in there (which may have been intentional, as I know the word has crossed the pond, if it's not common). That made me wonder, but the rest of it seemed very good and natural. (Like I said, silly compliment if you are British, but otherwise...)
I do have one suggestions for if/when you reform for posting elsewhere ... would it be possible to indicate the *year* beside the title of the prologue and again beside the first chapter. I was confused for a bit as to just how old Teddy was there for a while. I did eventually figure it out, but without an immediate hint, I sorta assumed that Chapter 1 took place in the same year as the prologue, where he'd be a 5th year. I was also a bit confused about whether he WAS a 6th or 7th year, since he seems to be in his NEWT year but is still a prefect, and I understood that only 5th and 6th years were prefects, while the Head Boy and Head Girl were 7th years. (Maybe because the 7th years are legally adults?) Anyway, that one issue of time tripped me up, so I thought I'd mention it, but really, I SO enjoyed this, I hope you don't mind the suggestion. :-)