Looks like Harald may have been another Imu victim, that Imu passed a contract on to be the leader of Elbaf as an insurance for Elbaf's military power to stay under his control
Harald may have actually been good and the beginning, but ended up manipulated like Gunko, Dorry or Brogy, and thus Loki was forced to kill him, which also explains why he said they should know that he did something he didnt want to do
It also indirectly suggest that Loki also knows how to bypass Imu's regen