A fanlisting is simply an online list of fans of a subject (in this case for Innes) that is created by an individual and open for fans from around the world to join.
There are no costs, and the only requirements to join a fanlisting are your name and country. Fanlistings do not have to be large sites (although some are), they are just a place where you can sign up with other fans. TheFanlistings.org is the original (but not official) web directory for fanlistings, dedicated to uniting the fans.
Description from TFL.

Innes is the Prince of Frelia and Tahna's brother. He's a very skilled archer, peraphs the best one not only in his reign, but all over the continent. He's a really proud person who's always trying to show his valour and his abilities, and that's why he's qualified as Ephraim's rival. Although they quarrel a lot, I think they're very good friends, although they surely need to stop their attempts to determine who's the best one between them. Innes is quite successful with woman: he can be paired with several female characters (Eirik and Larchel for istance), and it's sure that Vanessa has a big crush for him. My favourite pairing for him is actually Larchel.