Definitely not suspicious at all.. =D
First she called mc by her real name instead of the name she had presented herself with. (Most likely a reincarnator, but even if she's not that's a huge sign to be wary of.)
Within less than a day from her speaking about wanting the place, all money from all stashes got stolen without any others visiting so it must be one of those present, and she's the only outsider and thus the only one that didn't get robbed. Her wanting to actively help search only makes her more suspicious, partially for being the only one not belonging to the household.
She looked rather happy about the situation while still among them, while they're discussing how they'll struggle to manage, as if she's glad to confirm they didn't have more money besides what was stolen. (She even got to search through their stuff in broad daylight, probably another part of why she seemed so content "despite" their dire situation.)
Then within two days total from her speaking about wanting the place, the demands because someone placed a huge bid on it, enough time that sending a messenger back and forth would be possible.
Don't forget she didn't even hide that she's from one of the few families with power and wealth enough to even do something like that.
Definitely not suspicious at all, am I right? =p
(And so far I've only brought up points that should be pretty obvious even for those that haven't developed a sensitivity for identifying poisonous people already.)
Still wouldn't surprise me if she besides carrying a grudge for mc running a clinic where she wants to have her villa, (quite likely just to fit the storyline too)
also carries a grudge because she was supposed to be taken care of by someone else. (Which didn't happen since there now was a clinic that they carried her to instead.)
Well, least bitchy move next would be something like the actual bidder being one of her capture targets and them getting closer in the game through the interaction of him as someone attempting to buy and her as the owner.. And her trying to improvise to get similar results by jumping in as a sort of representative here. (Unlikely but it's the least bitchy conclusion that actually aint unrealistic.)
