It is without a doubt how Klaus and Caroline's relationship way back in "The Vampire Diaries" has set so many hearts on fire. Thus, it can't be questioned how many of the fans are rooting for them to be the end game for the spin-off, "The Originals" and how they are hoping for Carline to crossover to the series once its predecessor comes to an end.
Klaus Indicating That He Wanted To Be Caroline's Last Love, No Matter How Long It Takes
There are many reasons to back up speculations on why Klaus and Caroline should end up together in "The Originals," despite the writers giving him another potential romantic storyline. For one, the greatest aspect of their relationship that the fans are holding on to was the scene during Caroline's graduation wherein Klaus tells her he intends to be the last love of her life, no matter how long it takes. Amidst Klaus's gruesome and cruel personality, he has always had a soft heart with Caroline, and only her. They had a connection undeniable to the viewers, which made them love Klaus all the more, thus leading to the success of "The Originals."
Klaus Only Showed His Humanity Every Time He Was With Caroline In "The Vampire Diaries"
It is no doubt that one of the factors that led to the fans living Klaus's character was his softness with Caroline. He was the big bad wolf of "The Vampire Diaries" and from being the biggest villain of the show, he became his own hero. He showed his humanity because of his love for Caroline. He used to love to make fun of her during their time together in the series, which led to the viewers seeing the lighter side of him; the more humane side.
Klaus Wouldn't Be As Loved As He Is Now If It Wasn't For Caroline; From A Villain He Became A Hero Himself
Many have doubted that "Klaroline" will be the end game ever since Stefan proposed to Caroline in "The Vampire Diaries," one which she said yes to. However, it can be seen that Stefan is still carrying a lot of baggage within him that it may be hard for them to have their happy ending. Also, Klaus wouldn't be as loved as he is now if it wasn't for the subtle ways he showed how much he was in love with Caroline. He wouldn't be considered a hero, or even human at that if it wasn't for her, thus there is no other salvation and redemption for him other than Caroline.
"Klamille" Relationship Is Nothing Compared To The History Of "Klaroline"
In "The Originals," a romance between Klaus and Camille was tested into the waters, but the latter was already considered dead during the last season. Although it is still highly possible she survives and becomes a vampire in the upcoming season, they have so many issues within themselves that can't be solved by being with each other. There is too much baggage in that area that will deem impossible for them to work things out, especially that their chemistry is nothing compared to what Klaus has with Caroline.
Joseph Morgan Who Plays Klaus Also Ships "Klaroline"
Lastly, actor Joseph Morgan who plays Klaus in the series has already said so himself that there is still hope for "Klaroline" to come into the light at some point. If he hasn't lost hope in that ship, neither did the fans. With "The Vampire Diaries" coming to an end, it gives a very big room for Caroline to crossover to "The Originals" and make true of her romance with the Klaus.