Realizing what's happened and that Helge is involved in the disappearance of the young boys, including the deaths of his brother and son, Ulrich attempts to kill a young Helge (Tom Philipp) in 1953 so he can't kidnap children in the future for Noah.

Did Ulrich kill Helge?

He finds Helge as a middle aged man and attempts to kill him, destroying his eye in the process. As soon as he finishes bashing his eye in, Ulrich takes him into the bunker, possibly to kill him for good. An old Helge then comes to the bunker and kills him.

What is wrong with Helge in dark?

Noah eventually sent Helge back to the 50s, where another version of the priest stayed in contact with the child. By the 80s, Helge was working for Noah and helping to kidnap children at his behest and covering up other misdeeds. He was also revealed be psychologically damaged and almost blindly following Noah.