Let's go over some of the "irrelevant" decisions Kerrigan made while "brainwashed" in the vanilla zerg campaign:
1) Spared Jim Raynor's life against the Overmind's command that all Terrans should be destroyed.
2) Disobeyed Daggoth's directive to destroy the Garm Brood and went to hunt Tassadar and the Dark Templar instead.
3) Went to increase her powers instead of humbly serving the Overmind, to Zasz's chagrin.
4) In Queen of Blades, she flat out told the Overmind that no, she does not want to go Aiur to lead the battles like the Overmind originally planned, and would rather stay to hunt down the Protoss.
5) In the original game, she effectively got Zasz killed because she fell for Tassadar's diversion (though that was retconned out of queen of blades).