The two of them worked closely together, perhaps to close it seemed, as their professional partnership and become a romantic relationship; something that was highly against the professional atmosphere that the Council had tried to instill within the Spectres.
Nihlus had begun to fall in love with Primora, something that proved nearly fatal. On a patrol deep within the Nemean Abyss, Just hours before Nihlus planned to make a marriage proposal to Primora, he had been ambushed by henchmen of the Kingpin, a mysterious, highly-influential, and dangerous crime lord that Nihlus had been tracking for months. After barely escaping the ambush with his life, Nihlus would learn that Primora was behind it, and that she had been working for the Kingpin for some time, leaking information in exchange for millions of credits.
Heartbroken and convinced that he could no longer trust anyone ever again, Nihlus began his hunt for the double agent with orders to capture dead or alive; Nihlus had no intentions of firing non-lethal shots. For days, Nihlus searched the galaxy for Primora, but it seemed she'd disappeared without a single trace.
Busting multiple known spots of the Kingpin's, disrupting numerous drug trades, and ending various slave smuggling routes put a strain on the Kingpin, but it didn't get him any closer to tracking down the woman that betrayed him. Beginning to lose any hope that he would find her, Nihlus would receive a mysterious message from an unknown sender one day. The message was short and simple:
Nihlus didn't trust the information, but with nothing else to go on how much could it hurt to take a look? Without much hesitation, Nihlus prepared his ship and headed way for Omega, the criminal paradise. Nihlus heard of Naz before, supposedly a small fry compared to the bigger fish on Omega but he could certainly make people disappear. Upon arriving at Omega, Nihlus' first stop is at the Afterlife Club. There, he is approached by a salarian of a particularly suspicious appearance.The salarian presents himself as Naz and lets Nihlus know that Primora and Kingpin think that Nihlus is dead, but suspect that his death has caused a crackdown by the Council.
Naz also gave up information on a plan that the Kingpin was hatching to defend himself against such a crackdown. When asked why he's giving up information for free, Naz replied by stating the end of Kingpin and his allies was fair enough trade for the info. After getting enough information, Nihlus set off to the Omega warehouse district, the location that was said to be where the Kingpin was having a meeting.
At the Factory District, Nihlus meets the Kingpin and a group of heavily-armed guards on their way out. Upon seeing Nihlus alive, the Kingpin orders his men to attack; all of which are quickly being gunned down by the vengeful Spectre. Kingpin flees back into the district with Nihlus not far behind. After battling through waves of mechs and armed thugs, Nihlus would find himself nearing the Kingpin's hiding place. The Kingpin thinks that Nihlus is dead for a moment, but is proven wrong once again when Nihlus ambushes him and begins questioning the criminal leader.
Kingpin is not exactly forthcoming of the whereabouts of Primora, which happens to be the only thing Nihlus really cared about at the moment. After the crime lord refused to cooperate, Nihlus resorted to beating some sense into him. After being beaten to a bloody pulp and having his leg broken, Kingpin agreed to tell Nihlus everything.
Kingpin had sent Primora on a mission to assassinate a few people who dared to oppose his rule in the criminal world and stated that once she was done with his foes in Omega, Primora would go to the Citadel to assassinate the Council.
Nihlus knew he had to stop Primora so, just after quickly executing the Kingpin, Nihlus took a transport back to the Afterlife Club where he discovered that the entire club was under attack Primora and a number of the Kingpin's old henchmen. Nihlus began mowing them down to get to Primora, but she caught on to his approach. She fled from the club and Nihlus was about to be dead on her trail until he sees the mortally-wounded body of Naz. Naz warns Nihlus that Primora will not be going directly to the Citadel but still has to go to one of Kingpin's safe-houses to wrap up business. As he lay dying, Naz asks Nihlus about the fate of Kingpin. After being informed of his death, Naz thanks Nihlus with his dying breathe.
Nihlus tracks Primora down to the lower districts of Omega where her safehouse is located. While she's inside of the safehouse, Nihlus prepares his sniper rifle from about two blocks away. His reticule is perfectly stabilized and his rifle is fully-loaded with armor-piercing rounds. Nihlus could see her through the safehouse's window. His aiming reticule was centered square on her skull but, out of all the rage of her betrayal, he had no time to realize that he still had feelings for her.
He knew that there might not be another time and, even though he still loved her, he had no choice; he pulled the trigger. With her body resting in a pool of blood, Nihlus knew that his job was done. He didn't know the details of Primora's treachery, he didn't need to; it would only make the decision to kill her tougher for him to deal with.
From that day forward, Nihlus became a solitary hunter, no longer able to entrust another being to help him. The only other person he still trusted was Saren Arterius and in time, he'd see what that trust gets him.