Very interesting parallels. Loeb was the instigator/mastermind (DM) and Leopold the enabler (MS) and only both together could lead to murder. .
There
are striking parallels between the Loeb and Leopold case and the crimes of DM and MS, but the similarities don't map exactly onto DM and MS. In our cases, DM is clearly the leader/instigator, MS is a petty criminal who has a kind of crush on DM (no real evidence of a sexual component, though) and aids and abets but doesn't seem to have been the planner/organizer. Though DM probably has above average intelligence, he is hardly a genius, and MS struggled in elementary school and likely had a learning disability of some sort. So, their roles were fairly discrete and complementary
With Loeb and Leopold, the contrasts are fewer. There was a sexual component to their bond, and both were highly intelligent and finished university several years early. Both were from rich and privileged families. Socially and intellectually, they were equals, though in their relationship Loeb was the leader, even though Leopold was academically much more brilliant. There's another parallel in that one was charming and gregarious (Loeb/DM) while the other was more of a loner with less social acumen (Leopold/MS). Loeb was like DM in that he had a history of petty crimes committed for fun and the thrill of it - burglaries, arson, vandalism - and he fancied himself a budding criminal genius (again like DM) but like MS, Loeb was a substance abuser (alcohol).
Loeb was the idea guy, and his idea to kidnap a child was similar to DM's scheme to steal a Dodge RAM, and had an implied potential murder as part of the plan. Leopold did not originate this plan, but MS-style he went along with it and contributed some ideas of his own, especially his admiration of the philosopher Nietzsche and the idea of the "Superman" who would be above the law and morality. Leopold was Loeb's faithful servant, rather as MS was to DM, though the nature of that bond seems to differ from between the two criminal pairs. There was indication of abuse (possibly sexual) in both Loeb and Leopold's childhoods, and we have speculated about that possibility with MS and DM. When the FBI did their in-depth studies of some 50 psychopathic serial killers, they found nearly all of them had sexual and/or physical abuse in their childhood.
It will be interesting to see whether the similarities continue. In prison, Loeb was eventually murdered by a fellow inmate, his personal charm notwithstanding. Leopold engaged in positive activities in prison, was eventually paroled, married, stayed out of trouble, and worked in the medical field for some years. It would seem the follower in a deadly duo has a better chance of rehabilitation than the instigator.
There are a couple of documentaries about Loeb and Leopold on YouTube.
Compulsion is still the go-to book on the crime. It is, well, compelling. And it suggests that history does indeed repeat itself.