The confidence does stoke a certain degree of curiosity. How couldn't it? It also drives home the strangeness of their situation. Percy has experience with her that she doesn't share, in a way that puts her somewhat at a disadvantage.

Somewhat.

Vex is still very sure she can blow his mind, thank you very much.

As if to prove that, when they reach the top of the stairs, Vex wheels on Percy, cornering him between her body and the wall while she goes in for an assertive kiss.