1.) Found! Thanks everybody!! I've been trying to edit the tags to reflect this and hopefully it will show.I'm looking for a story I read back sometime in 2010-2011 (wow, look at the time!). It had a completed sequel and I think the author was writing the next one at the time. The first story was set in Glee S1. I think Kurt observed a number of alternate universes and I think he even stepped in and mentally tried to stop an AU!Kurt from doing something regrettable at a school. He meets a young woman (who's probably an alien) and I think she was supposed to just observe him but she became sympathetic to everything that was going on and tried to help him.
The sequel was set in S2. The Warblers check up on Blaine and discovers that he's physically a child. They send Kurt back home, call up on the Glee club and try to figure out what to do before Kurt mentally becomes a child as well. Kurt wasn't in a relationship in Blaine at this point and I think they were still 'dancing around the idea' even towards the end.
2.) I haven't watched Glee since the end of S2. I'm looking for some recommendations of fics that you believe should be Glee classics. I don't mind if it goes beyond S2 as long as it's well-written. I am heavily biased towards Kurt and if you know of a fic (preferably gen) where he experiences a personal tragedy but manages to persevere, I would love to read such a fic. But otherwise, I want to know what I've been missing out on after all these years!