She had it in her power to make him miserable and unhappy.

She would enjoy seeing him unhappy! The meanness of the woman who longs to injure the man who loves her, whether loved or unloved, revealed itself for the moment in this fair-minded, generous girl.

(It is a common trait, admitted by many fair-minded and generous women!) But even as she coddled and encouraged the little sprout of vengeance, the chill of common-sense rushed up and blighted it.
She had a sickening impression that Percival would fail to play the part according to her conception.

In fact, he was quite capable of not playing it at all.

He would pursue the even tenor of his way--( she actually made use of the time-honoured phrase in her reflections),--and she would get small satisfaction out of that.
Moreover, there was Olga Obosky to be reckoned with.