That's very interesting. I think I've found stories written post S2 often feel more secure about Jack and Ianto's relationship if that makes sense. Even though it was clearly there is series 1, a lot had to be added to the canon. Or speculated or something. Plus I think after CoE people felt a need to give them an even happier ending than maybe before? Having said all that it could also be my bias as I found myself not wanting to read some stuff that I may have read pre CoE. Plus I don't read non canon pairings, so may have been missing all sorts of things. (It's not a policy or anything, I just find I never feel convinced by them and I waste enough time reading fan fiction as it is. )