I don't really like the idea of this as a @command. Far to many ways for it to be abused.
Stealthy people as mentioned. - if someones stealthed and following you, it defeats the purpose of it if the followed people can trigger a command to see theres an extra person in the area. "locked doors" is more a defeat, if they managed to follow you into that, and then you have the command to see theres another with you.
PvP - Oh, I'm chasing this guy... he was in X map, now theres a guy on Y map... "follow follow". Likewise, someone out corpse hiding someone or something, the ghostly character can just follow the hiders likely progress with such a command. "OH look, one person way out of the way in this place, must be where my corpse is"...
Instead of doing a random 'locator', how about we think of ways to better seek out and incorporate people into our RP? Hold some sort of event, to bring people to YOU, or something. Seems more fruitful then just putting yourself in an area with people you may have nothing to do with, in a location you'd have no IC reason to go save the OOC command.
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I do like the idea of the fortune teller, if such is a desirable thing. Makes it an ICly thing, giving you reason to head somewhere. Could perhaps instead of listing ALL the areas... just like the top area, or the top 3 areas or something, with the most people. Perhaps keeping it to 'public places', if such could be scripted (to avoid say, oh, theres 6 people in "Barovia - Lady's Rest - Evil Cultists Secret Hideout").