Change Of Heart

Not like a heart transplant, no.

When someone has a Change Of Heart, they totally transform in the way they think, either momentarily or permanently. This can be because of what someone told them earlier or they finally come to decide that what they were Mere Moments Away from doing was wrong and they should stop before it's too late and do something they'll regret. This perfect timing is called an Emotion Ex Machina. Someone might have a Change Of Heart when they have nothing and no one to oppose them and prevent them from succeeding, but the plot says they need to cut it out because as nothing and no one can oppose them, there needs to be a convenient Plot Saver that plays in that very moment, making all the effort put into coming as far as they did effectively void. Someone can also fake having a Change Of Heart to catch their enemy off guard and attack when they least expect it.