Del never could explain it. She had meant it to be a simple transaction. Tiger was but a step on the path toward revenge and saving her brother. Then he was a useful tool, to regain her daughter. Possibly there had been a sense of moral obligation with the aftermath and Tiger being possessed.
She was not going to admit to being maudlin, needing companionship, or ice-forbid-it such a thing as love.
Better that she just leave it in her own mind that Tiger was hers now, by dint of being too stubborn to break on her own stone walls.