D'jinn does not like this man at all. He thinks he is best because he is Nord, and says rude things to D'jinn's Dunmer friends. D'jinn attempted to talk to him, and he challenged her to a fight. No magic allowed, he said, only fists. D'jinn won of course, her claws are fast and sharp. The Nord stood no chance against her. But he still did not stop shouting at the Dunmer. He continued to say rude things, that they should "go home," when everyone knows full well nothing is left of their home. D'jinn could not listen to him anymore, and took matters into her own claws. She easily killed him, and the guards did nothing. But why does Rolff not stay dead? He simply falls to the ground, lays there a few moments, then gets up again and D'jinn takes him down easily again with fire. She could do this all day.

Reading the wiki, D'jinn sees that he is classified as "important" due to the Fishing Job quest. But D'jinn asks, after this quest is complete can he be killed? D'jinn does not want to listen to his rude words any longer, and is sure her Dunmer friends do not want to either.

AFAIK, anyone classed as "important" is unkillable forever. Probably after the CK comes out that will change.

And as soon as he is, this Argonian Warlock will have a Dremora Lord all over him.