Klaus himself seems afraid of him for some reason, although Kol doesn't seem to be more of a danger to him than the other siblings.
They all were mad and probably wanted revenge, this probably worried him because of course they couldn't kill him but they could've messed up his plans. And with Kol being the most reckless Mikaelson, and second vengeful. He would've showed no hesitation to ruin something very important to his brother for revenge.
Esther is, along with Mikael, one of the two beings that Klaus truly feared; Klaus is only afraid of Esther, because she knows the Spell that turned him and his half-siblings into vampires, or in Klaus' case into a hybrid, and can turn them back into humans again, or in Klaus' case into a werewolf again; however, ...
Klaus hypocritically explained that Kol's actions toward Rebekah had earned him that spot, since he cared more for Rebekah than Kol, going so far as to say that Kol could rot until he found Rebekah. However, he still wanted Kol protected by Marcel, only till they found Rebekah.
Kol Mikaelson
He's not more powerful than Klaus or Elijah but he was also able to kill twelve vampires single-handedly; so clearly he has a lot of prowess. Kol has proven that he can hold himself in a fight against Klaus, which means he's definitely had a lot of strength as an original vampire.
Klaus Mikaelson
As the only Original Hybrid, Klaus has combines the raw powers of both Original vampires and werewolves to become the most formidable foe on the show. While his character also vacillates between good and evil, his power cannot be eclipsed.
Though Kol, being an Original Vampire, is physically stronger than Damon, Damon has used the element of surprise to put up a fight against Kol in their skirmishes.
Kol is at least two years older than Rebekah, and Klaus is at least 1 year older than Kol. Going by appearance: Klaus is 23-24.
When Finn (Yusuf Gatewood) cursed his younger brother Kol (Daniel Sharman), we didn't think the show would actually go through with killing him off! But alas, that's exactly what happened tonight, as Kol succumbed to the curse, surrounded by his loved ones, finally feeling like he belonged in his final moments.
Rebekah was arguably Klaus's most treasured sibling.
Klaus became the deadliest of the originals because of his hybrid nature. He also parades around as the more feared of the two with his vagrant displays of aggression and flippant regulars for life of all kind, but let there be no mistake— Elijah was truly far scarier.
Lucien even proved to be much stronger than Klaus, the Original hybrid, during their confrontations. Similarly, Marcel was also stronger than the Originals and Klaus, fighting them with ease. They are quite possibly the fastest known creatures as Lucien was able to dodge Klaus' attacks effortlessly.
So Kol's afraid of Silas, because it's said that he'll bring the end of time.
As an Original Vampire, Kol is one of the most physically powerful beings and most skilled fighters on the Vampire Diaries and Originals universe.
Despite his lust for power, Klaus still cares about the remaining members of his family. Despite being manipulative, he does not like being lied to or manipulated. He does not take being betrayed very well, especially if it is from a member of his family. He is intolerant of people who disappoint him in general.
Henriikka Mirai Darina Mikaelson, more commonly referred to as Henri or Riika, is a major recurring character on Legacies, though she was first appeared in season five of The Originals. Henriikka is the hybrid daughter of Kol Mikaelson and Davina Claire-Mikaelson.
When Kol tries to cut off Jeremy's hands, Elena intervenes and Jeremy kills Kol with the White Oak Stake. Klaus sees this, and threatens to burn the home to ground and that he is no longer worried about the cure or his hybrids.
In season two of The Originals, Kol was briefly recast with the Brit Daniel Sharman – explained narratively by his possessing Kaleb Westphall's body.
The writers usually spell out things that important “originals grow stronger with age”, but they never did because originals are already the strongest they could ever be. Only modifications enhances them. The spell just made them more resilient and able to compel their progeny, it didnt put them at peak.
The laws governing compulsion of Original vampires also apply to Enhanced and Upgraded Original vampires. However, with Vincent's aid as a witch, Marcel Gerard was able to compel Elijah, an Original vampire.
Elijah Mikaelson is the second-oldest of the Original vampire brothers (and the third-born child of Mikael and Esther).
Klaus is far more powerful than Silas because he's physically the second most powerful thing walking the planet (behind the Beast of the prophecy). Silas wasn't even as strong as a vampire, he's barely stronger than a human.
With the death of Mikael, Klaus Mikaelson, Elijah Mikaelson, Lucien Castle, Alaric Saltzman, and Finn Mikaelson, Hope is now the strongest creature on the planet only rivaled by the last remaining Originals ie; Rebekah and Kol Mikaelson but possesses an edge over them to her hybrid nature and her only equal is possibly ...
Mikael has proved many times that he's stronger than Klaus, and of course much more powerful than his other children. Many fans have questioned this detail, but it makes sense. Mikael was already a revered Viking warrior when he was turned by Esther into an original vampire, while Klaus was an untriggered werewolf.