He was living on Mota at least seven months prior to the game. He tried to kill Nei, but was apparently stopped, perhaps by Rolf.
His daughter is kidnapped some time prior to the beginning of the game by scoundrels, who demand a large ransom in exchange for her return. Unable to pay the sum, he has taken to robbing or killing passers-by over on the North Bridge, effectively shutting off passage, showing that of his anger.
After rescuing Tiem from Nido Tower, Rolf, Nei, and Rudo return her to Darum. She ran up to Darum, but as she was disguised, Darum did not recognize her and demanded money. When she refused, he struck her through with his sword. Once he realized what he had done, he was grief-stricken and committed suicide by blowing himself up. After taking a moment to reflect on the tragedy, the group continues their journey to the Bio-System Labs.