I didn't recognize it at first, but Ms. Crater also had a hidden agenda, but I argue that her agenda was actually developed a little later in the story once sees how valuable Shiftlet presents itself. There are many times when he appears to be graceful and attentive to what he is doing. I remember in the story when he initially said he didn't want money and later Shiftlet got offended when Mrs. Crater threw money in his face. He also unintentionally gives her a moment of grace when he seems to acknowledge his feelings for his daughter. Lucynell is mute and has an innocence that compares to a 15-16 year old girl, while Shiftlet has half an arm and struggles to be accepted in the outside world. All of these elements prove that O'Connor is trying to tell us that it may not have been a coincidence that these characters ended up with each other.