Giselle was a petty criminal that Jack first encountered in Spain, but Jack saw in her an ally, and she became key to the secretive world of Jack's empire.
Like Jack she her character was formed by her early life, and in other circumstances she might have been the society lady from the start.
Through her association with Jack she is lifted from what might otherwise have been a downward only spiral.
By the time she meets Justin there is little of the girl his father encountered thirty years earlier.
It is through her that Justin is able to resolve the puzzle behind his own history and his mother's good fortune.