Can I trigger its response if there is no power on characters?

Provided that you lose a challenge, sure. Not entirely sure want you'd want to…..

rayind said:

Ellaria is not androgynous.

dcdennis said:

Cards have no gender

And even character cards are referred to as "it" in this game (unlike other games where human characters are referred to as he or she).

ktom said:

He wants to cancel it with "He Calls it thinking".