Thane, are those your sketches? I love them.
I've been on these boards for almost a year and only just found this club. I love this totally crack pairing which was so nearly possible and in an AU could well happen. These two could actually make each other happy. He really does understand her. They say that in every relationship there's always one who loves more, and I think Tseng would always want to be the one who loves rather than the one loved.
Normally I promote other people's fanfiction, not my own, but in this case may I humbly suggest that you might enjoy reading:
http://archiveofourown.org/series/2338
It's a mammoth novelisation of BC and CC combined, and it's a WIP. Because it's handling so many plot threads, it takes a while to get round to Tseng and Aerith, but it does go into their whole backstory in some detail. There's also Zack/Aerith, Zack/Cissnei, and Reno/Cissnei. If you give it a try, please let me know if you like it.