>>529319729
Kris doesn't have an ON/OFF switch, the level of control we're exerting on them varies. Kris ordinarily has a significant degree of agency to act on their own will, they're compelled to obey our commands but they can express themself in doing so and even undermine what we're trying to have them do. They're not a robot that needs to be told to sit down, they can act and speak on their own without our commands. But our control still inhibits them - Noelle states that Kris's voice sounds like they're "on speaker" even in the normal route, and Kris isn't able to play the piano as well as they could on their own, even if we hit all the right notes.
In Chapter 4, we are required to relax our control over Kris enough to let them play the piano freely in order to progress. And conversely in the Weird Route, it's shown that we are capable of asserting total control over Kris, forcing them to be our mouthpiece and do things that they absolutely DO NOT want to do.
It's a simple question of Determination, and WE will always win that battle.