The Villainess Gets her Sponsorship

Katrin Elemore wakes up inside the novel “Star of the Revolution.”
She is now the villainess who fights against her favorite hero, Etias, and she is first on the purge list.

Then the author gives her a mission:

“Forget dull text. As a character, help Etias in real life!
If you fail the conditions, you will simply die. Good luck.”

So Katrin must hide her secret help for Etias and support his revolution.
If she is caught, she dies.

Katrin cheers him on in secret:

“Etias, stay strong!”

Yet to his face she acts like a rich, arrogant villainess:

Etias: “It seems you really enjoy tormenting me.”
Katrin (coldly): “You’re mistaken. I’m only doing my duty as His Majesty’s loyal subject.”

Her plan is simple: fund Etias quietly, flee to a neighboring country once the revolution starts, and feel proud when he succeeds.

But things go wrong. Etias’s cool blue eyes lock on her.

Etias: “You supported me, so take responsibility. Stay by my side forever.”

How did he find out?