…I have to ask if seriously changing the nature of the school leaving and school entering ages is necessary to your plot.
Originally, I decided to age everyone up so I could avoid the whole chan issue. A lot of HP fic archives I’ve come across require that all characters in NC-17 situations be 17 or 18 and up, and I want to keep my archiving options open. Also, I feel more comfortable writing graphic sex for people age 18 and up, than I do for 16 and up, anyway.
Now that I’ve aged them up and plotted with that in place…it’s kind of locked in. Basically, Severus and Lily being 18 is hit upon and dealt with in the fic often enough (at least for Story Arc #2, which takes place during the summer holiday after OWLs) that it’s too late to change it, at this point. ^_^ Basically, those last two years of Hogwarts are like a junior college experience, with Severus and Lily being like college students who come home for the holidays and deal with the gray areas of being adults and yet also being their parents’ children who are still in school. With magic! And wizard vs. Muggle conflict (esp. with the also visiting Petunia and with Snape’s parents.) I think it’s a fun thing to explore during the start of Severus and Lily’s romantic relationship, and I haven’t seen it done in Snevans fic, yet, so I’m hoping that makes the age change a worthwhile canon deviation, for my readers.
At Hogwarts, the age change doesn’t make much, if any, difference. And reaching wizard majority didn’t seem to make much difference for the 7th years going to Hogwarts in canon, either. So, it's no big whoop when they're at Hogwarts.
This would have had serious knock-on effects not only for Snape's generation of the 1970s, but Arthur Weasley's in the 1960s and, in future, Harry Potter's in the 1990s. In short, this one change could cause not just minor, but major incalculable changes.
For my AU, the characters are pretty much the same as their canon selves during the same time period as the start of the fic (1976 for canon, 1978 for fic). Maybe two extra years didn’t make that much of a difference for most people. (Pay no attention to that woman behind the curtain!) Or maybe readers could use the age difference to explain the reasons for the characters being a bit different then they interpreted from canon, if they are different (since even among the sane fans, there are some different interpretations). For instance, maybe those two extra years helped slow Snape’s descent down the dark path, and maybe those two extra years increased Lily’s romantic feelings towards Snape. And so forth.
I’m basically hoping that the age change is an acceptable break from canon that readers are fine suspending their disbelief for or fanwanking to their satisfaction.
What would Tom Riddle have been like, entering school at 13 with two more years of terrorizing kids at the orphanage? He was bad enough at 11, but with even more dominance-seeking and antisocial behavior ingrained into him at 13 he probably would have become an even crueller Voldemort (if that's even possible! O.O ).
Yeah…that is a good point. If I’m going to fanwank it (and I will) I’d say that Voldemort was so messed up already by age 11 that two more years didn’t make much of a difference for him. He’s such a freakin’ whack job in canon, how much worse could he get? XP
If you have any more questions, feel free to ask. And I hope you’ve enjoyed the fic enough to keep reading. ;)