I was wondering how the plot of TO may be made richer and I have come up with an idea that makes a lot of sense to me and maybe will to other fans as well.What if we say that Esther bound Klaus' wolf side because he had caused Henrik's death.. hear me out like Klaus lied to everyone that he was a wolf (only his mother knew) to save himself from Mikael's wrath.What his mother didnt know was he bound his curse before she did! Here is where the story grows) He had caused a death as a kid to some random person and spent his life in the new world trying to bind the curse hiding from his family during transformations.He found a witch to help him who told him that for the curse to be bound he had to have an original werewolf kill someone from his family( a life for a life trade) .He had Henrik secretly spelled and lured him out to get killed by an original pack. Problem was the witch had not counted on the cursed Klaus being made original for when Henrik died at the hands of original werewolves, upon Klaus being made original the law of magic dictated that the curse had to be bound in a pure werewolf since Klaus ceased to be pure it went back to re- animate Henrik becuase of 2 critical caveats 1.Since he died from original werewolf bites we find out his body would have transitioned and turned him into a wolf as original werewolves like vampires have that ability of turning humans into wolves if they bite or scratch them and 2. Since Henrik was part of the trade he was linked to Klaus when the deal with the witch was made and since Klaus remains alive so does Henrik.
So in the originals we find out Henrik is alive and is an immortal werewolf looking to have a way to destroy his link to Klaus and he can only do so by killing Klaus' child and so we have klaus having his own brother as his greatest enemy.
PS: Henrik could be played by a mature actor if we explain his first transition as a werewolf changed him