Laura Fermi

Laura Fermi definitely plays the part of femme fatale with her cryptic behaviour. On one hand, she shamelessly uses her massive sex-appeal to gain the upper hand when needed. On the other hand, she displays an unusually high intelligence and sense of self-preservation, as seen during the HQ's invasion by Gon. Origin himself remarks that she's dangerous, not because of her appearance but because she's an expert at concealing her actual motivations and goals. In short, her Hot Scientist act is indeed just an act but even Origin can't determine what Laura is actually after.