I've pointed her at AO3 but she doesn't like it. Apparently, its layout isn't as nice on the Kindle. The tag headers come out as a list instead of a paragraph, and they're repeated at the top of every chapter; she doesn't like scrolling past them.

I'd make a suggestion to AO3's coders, but I suspect this is mostly a matter of the Kindle's very limited web browser's abilities. FF.net doesn't have the same kind of tag-based setup.

Also, FF.net has more of the fandoms she likes. There's just not that much Pokemon and Sonic fanfic at AO3.