These stories deal with the time before the Great Change, as Dr. Bell was testing (or in one case, acquiring) his formula.
Chronologically, this is the first in the Omar Bell Universe stories. In it, we see that the basic formula which caused the Great Change originated with someone other than Omar Bell. This is a simple revenge story in which a bullied boy becomes a a brilliant, but troubled scientist who hatches a plan to feminize the bully who tormented him.
This is the second in the OBU timeline (notice a theme here?). In this story, a man who makes his living robbing drug dealers is caught and punished by a man from whom he has stolen. More importantly to the lore of this universe, though, this is one of Omar Bell's first test subjects.
This is the final of my prequel stories, and I think it's probably my personal favorite of the three. In it, a man who has been blamed for a mistake he did not make, loses his job. So, he sets out to punish the man he deems responsible - the boss' nephew who had actually made the mistake for which the man was fired. At first, he sets out to punish him by conventional means, but before he can, he meets an old friend from college -- Omar Bell -- for dinner. Together, they come up with a plan to really hit the guy where it hurts -- by feminizing his son.