I can't find the scene on Youtube so let's see if my memory holds up. Iirc it's when Viren (the main antagonist) is imprisoned and he tells Soren and Claudia (his two children) to kill the two protagonists. When they fail and confront their father about it, he tries to gaslight them into believing he never told them to kill the princes. Soren doesn't fall for it but he's the comic relief character, so Claudia believes it and throws her brother under the bus.
So yes, Claudia ended up agreeing with Viren on Soren being too stupid to realize what was said, but it's played as a serious moment and it's what causes Soren to defect to the protagonists' side.