The Originals is a weird show. The four characters who came over from The Vampire Diaries to form the bedrock of the show's cast were among the least sympathetic on the parent show, and all the new characters seemed either forgettable or sort of horrible. But slowly but surely, The Originals is finding a story to tell.

Spoilers ahead...

And a lot of show's newfound watchability comes from the fact that the newer characters, like Marcel and Father Kilian and (to some extent) Cami are starting to get some facets, and some credible motivations. But also, this vampire spin-off is sinking its teeth into a richer vein of history, leading to something with more thematic power.

The first few episodes of The Originals offered us themes like, "Family is important," which might be better suited to a greeting card than an hour-long TV drama. Last night's "Fruit of the Poisoned Tree" still held out some heavy-handed themes, via a William Blake poem and a quote from Shakespeare's Henry IV Part 1 (sadly not a Falstaff quote) — but then the show actually reached for some real depth, by touching on the root of Marcel's ambition: his past as a slave on the plantation where Klaus now lives.

In some really terrific scenes with one of his daywalker lackeys, Rebekah and his former lieutenant Thierry, Marcel reveals that the reason he wants to be king now is because he had nothing when he was a child. As a slave, he would be beaten for taking a bite of one of the apples on his plantation — even a rotten one — so the apple Rebekah offers him has an especially bitter meaning. And then he realizes that Klaus is not only conspiring against him, but actually living at the plantation where Marcel was a slave, and his sense of betrayal is palpable.

All credit to Charles Michael Davis, who did such a robust job of selling Marcel's swagger that I was starting to think he was kind of a one-note performer — he brought real vulnerability and doubt to Marcel in "Poisoned Tree." And that nagging sense we've had in previous weeks, that Marcel is probably the most sympathetic character in this whole misanthropic tangle, has blossomed into a near-certainty.

This really is a show about a psycho vamp who helped build New Orleans, back in the age of slavery — and now that a former slave has pulled himself up and built an empire of his own, the former master has returned and wants to take it all away, simply because he can't stand to see anybody else have something.

In "Fruit of the Poisoned Tree," Marcel's realization that Klaus has played him (and has done so in a way guaranteed to rub in Marcel's slave past) is just one plot strand — the other ones involve Cami and her uncle the Priest Boss dealing with the knowledge that Agnes the witch cursed Cami's brother to go nuts and kill nine other priests along with himself. And Agnes kidnapping Sophie and using Sophie's link with Haley to try and cause Haley to have a miscarriage — only to have Davina undo the link at the last possible moment. Oh, and there's also Elijah forgiving Klaus for daggering him for the millionth time, and showing that he can be a ruthless dick too.

But although those other plot strands were pretty interesting in their own right — and I guess you have to applaud this show for zooming forward with the "witches need to complete the Harvest human sacrifice spell" plot it only just launched last week, by killing off Agnes, the one witch who could have completed that spell — the rest of the episode wasn't nearly as memorable as the glimpse of Marcel's other facets.

Klaus, of course, rescued Marcel from slavery and taught him to be a proud man even before turning him into a vampire — Klaus was the Dr. Kim Schultz to Marcel's Django. But at the same time, Klaus was always in a position of power over Marcel, back when they were friends, and a running theme with Klaus has been his need to enslave others. (Like his Hybrids, whom Haley freed from the sire bond so Klaus would murder them all, back on TVD.)

Klaus envies the loyalty that Marcel commands among the vampires — but Klaus will never earn loyalty when he can just as easily make you his slave. We saw that again and again on TVD — and just this week, Klaus seemed perturbed that Cami doesn't love him, after he's been controlling her and using her all this time.

And slavery is in the DNA of this universe — the early seasons of Vampire Diaries were forever flashing back to the Civil War, where the Salvatores were Gone With The Wind-ing it up all over the place. It's become a cliché to say that vampires represent our fear of the rich while zombies represent our fear of the poor — but this show has often held up vampires as slavers, and asked us to sympathize with them. (Or at least lust after them, I guess.)

So when Klaus attempts to put Marcel back in a subordinate position, and goes to live in the house where Marcel was a slave, the message is pretty clear. I just hope this show will have the guts to follow through on that idea. According to its title, this show is about the Original Vampires, the people who unleashed a thousand years of mind control, dubiously consensual sex and serial killing on the world — so it's fascinating to think that this show could use that supernatural motif to explore America's original sin. (Well, apart from Native American genocide.)

And just like that, The Originals is starting to get interesting.