The only way 'officially' was to search linkshells in the Linkshell Community (http://fanzone.playonline.com/lscom/index.do) -- but you can't really search by player name.

The unofficial way is FFXIAH.... this at least records character activity, at least if they use the AH at all. Maybe more info if their profile is available.

In any case, the Fenrir world still exists, so there's that.