Gah, I hate it when that happens... though I've more often had the reverse problem, with others knowing way more about my characters than they should. It's so often really hard to effectively RP into a pride when starting as a loner, because as soon as the players know that my character is harmless, suddenly every lion in the pride trusts him without question, even when he's given them no reason to. I've literally had Newt in mid-post, hiding around the edge of a pride's territory trying to tell if it's safe to approach them, and inevitably, no matter how deliberately suspicious I make my actions, one lioness will always run right up to the hidden-from-view, unfamiliar lion encroaching on her territory whom she knows nothing about (not to harp on realism with talking animals, but, y'know, rogue lions have been known to kill cubs, even if we both know Newton wouldn't) and says "Hi there! Want to join the pride? I'm sure [leader] won't mind!" I don't know where I should even go from there. I usually just have whatever character I'm playing become alarmed/unsettled/suspicious and hope the actual leader is less blindly trusting, but even then the tension is still pretty thoroughly killed and I end up sitting there in a pride full of unnervingly welcoming strangers not sure what to do with myself.
Honestly at this point, I wouldn't mind running into the 'get out of our territory or we'll make you into a rug!' type of pride once just for a change.
My other major pet peeve is characters who mysteriously change personality completely if they want an interaction to go a certain way, or just characters whose personalities don't match their bios in general. If your lioness is supposed to be shy and mistrustful of strangers, don't have her run up to me and strike up a conversation if we've never met. If your bio says 'cheerful, friendly, looks on the bright side' then why has your character been sitting off to one side of the group scowling at his reflection in a puddle and not talking to anyone for the last three passive-aggressively angsty posts?