The Original family in The Vampire Diaries was the literal first family of vampirism. When their youngest sibling Henrik died, matriarch and super-powerful witch Esther used her abilities to make all of her children immortal, and thus the vampire species was born.
However, despite the fact that Esther and her husband Mikael were willing to do whatever it took to stop from losing another one of their children, their family dynamic was extremely intense in many wonderful and terrible ways. But what were the worst and best relationships among the Mikaelsons?
Klaus & Mikael
There are definitely some troubled relationships among the Mikaelsons, but the undeniably worst of them is the father-son relationship between Klaus and Mikael.
Mikael didn't take it very well when he discovered that Klaus wasn't his biological child, but after Klaus offed his mom, Mikael seemingly devoted the entirety of his immortal life to finding and destroying Klaus. But even before things got supernatural, Mikael was blatantly abusive to his son, and they never seemed to have any kind of bond or love between them at any point.
Klaus & Esther
It's weirdly impressive that Klaus' worst parental relationship isn't actually with the parent that he murdered immediately upon becoming a vampire, but such is the nature of the Mikaelson family.
Esther and Klaus seemed to have a decent relationship when Klaus was still human, but Esther did lie to him about his parentage and didn't seemingly do much to stop Mikael from abusing Klaus even though she was an outrageously powerful witch. And once he became a vampire and then hybrid, Esther desperately wanted to kill Klaus to stop him from creating more supernatural monsters.
Esther & Mikael
Perhaps one positive thing could be said about Esther and Mikael as a pair. At least they were willing to do whatever it took to keep their children safe.
However, their marriage seemed pretty toxic even before Mikael and the rest of the children turned into vampires. And given that Esther is one of the most powerful witches in the world, it's a mystery why she allowed Mikael to dominate their family and didn't stop him from abusing their kids.
Finn & Klaus
Klaus and Finn's relationship didn't have a lot of time to develop in The Vampire Diaries, but it doesn't look like there was any love lost between them. Klaus had no problem keeping Finn in a box for the vast majority of his vampire life, and when Finn was released, their animosity became clear.
Not only did he appear to be Esther's favorite child, but he backed her up when she wanted to destroy his siblings and end the vampire species for all time. Klaus and Finn's perspectives on life seemed to be on the opposite ends of the spectrum.
Kol & Klaus
In contrast to brothers like Klaus and Finn, it seems like any discord between Klaus and Kol was caused by their similarities rather than their differences. They both seem to be impulsive, wild, and aggressive vampires who focus on their own wants more than anything else.
Kol is yet another sibling who Klaus kept in a coffin for an extended period of time, but considering that he wasn't boxed up as long as Finn, it seems fair to assume that he and Klaus had a slightly better relationship.
Kol & Rebekah
Rebekah and Kol didn't get a ton of screen time together, and it seems obvious that despite Kol being an enthusiastic vampire, he was never a part of the core Rebekah/Klaus/Elijah trio.
And, while Rebekah and Kol seemed to have a somewhat playful sibling relationship, they obviously lose a lot of points because Kol attempted to murder Rebekah when he thought she might raise Silas. Ultimately, Kol was correct that Silas was a huge danger, but he shouldn't ever have come at Bekah like that either way.
Finn & Esther
Finn and Esther's relationship is another that didn't get a ton of time to evolve, but Finn was obviously fiercely loyal to his mother above anyone else.
Kol literally called Finn their mother's favorite son, and despite being imprisoned for centuries and not seeing his mom for a thousand years, Finn was immediately ready to assist her in ending the vampire race. Finn may have had some moral objections to vampires as well, but the fact that he was unquestionably willing to help Esther kill his entire family shows that they must have a very close relationship.
Elijah & Rebekah
Rebekah and Elijah's dynamic seems to have a lot in common with Rebekah's relationship with Klaus in the sense that, while she's still a part of the core three, she's their slightly annoying and childish baby sister.
But despite the way that he dismisses her at times, it does seem like deep down Elijah has a lot of love and trust for Bekah. And that goes both ways, as while Rebekah sometimes disagrees with Elijah she still follows his lead in most situations.
Klaus & Elijah
To say that Originals Klaus and Elijah have a unique relationship would be an understatement. When they were introduced, Elijah was looking to kill his hybrid brother. But Klaus managed to outfox him once again, and daggered Elijah instead.
However, regardless of whatever they might say about wanting to be rid of each other for good, they absolutely do not hesitate to take each other's side against any threat, and given that they literally died together on The Originals, it's safe to say they have an unbreakable bond.
Klaus & Rebekah
While Elijah and Klaus did literally die together, the closest sibling relationship among all the Mikaelsons has to be Rebekah and Klaus.
The bar for a loving bond in this family is pretty low. But considering that Rebekah and Klaus never made any sincere attempts to murder each other and would seemingly never abandon one another in the end, they seem like the closest thing to a ride-or-die pairing within the toxic familial structure of the Originals.