As someone whose search for Abyss fanfiction has brought me to the kind of desperation that has me looking up IonXSink Chinese fanfiction (it's here
if you want it), and the occasional attempt to Babelfish Japanese (I do it once and then I swear off it forever, but usually somewhere within the next three months I'm desperate enough to try again), I'm going to list all the English Abyss fanfiction that I've ever read. I've done this every time anyone asks for Abyss fanfiction, so I'll just do it once and for all.
This is meant to be an exhaustive list - I am going to list literally all
the fanfiction there is
. Let me know if you've found more I haven't found, or if you'd rather not be linked.
Spoiler warnings apply for all fic. narugami wrote beautiful end-game fanfiction here. She also wrote an excellent AU here. And a lovely series on Jade, Anise and Florian here.
ranchelle and yukihyou have some excellent stories up here.
fate_repeated wrote Jade/Dist here.
pic_murasaki's Abyss fanfiction is on tales_of_yaoi.
chibimazoku wrote Guy and Luke, young!Luke and Guy, and Asch and Luke: on girlfriends. Really sweet Guy and Luke fic here, with art! All fic here.
Picup wrote a Yuria drabble (midway through page), a Natalia story, and a Guy/Natalia fic. [SO the Abyss fic has been hiding in the Symphonia category!]
Tear and Luke by griffinkhan.
I wrote some here and here.
There is a Tales of the Abyss fanfiction section on aff.net.
There isn't a specific Abyss fanfiction section on ff.net at the moment, but all Abyss fanfiction is going in the Symphonia section