Tales of the Nirshaddun

"The next step?" the Sangheili warrior asks, carefully thinking over the Spartan's words. At long last, he tells her "Nirshaddun."
"Nirshaddamn?" Cassandra asks. 
"Nirshaddun," the warrior corrects her. "It is a fell demon of folklore. It is said that such a creature stalks the night winds with armor made of polished shadows. Many warriors are eager to test their mettle against the demon, but the Nirshaddun always comes when they let down their guard."
"That's metal as fuck," Cassandra says.
=== Five years later ===
"Cass, I've been going over texts from our last cultural exchange with Sangheilios," Charles says. "And I've found more information about this Nirshaddun."
"Go ahead," Cassandra says, not interrupting her steady rhythm of slamming clips of ammo into magazines.
"The ancient tales do say that the Nirshaddun is a dangerous demon," Charles says. He pauses, and his avatar folds his hands. Clearly, the AI is devoting a lot of processing cycles to formulating his next sentence. "But, ah, in terms of comparative folklore, the Nirshaddun is really more of... it's, er, a succubus that preys upon very young warriors."
The rhythm stops. The Spartan's head turns like a Breakwater turret until her eyes are boring a hole through the holotank.
"What. Did you. Say." she demands, as a vision passes before her eyes of every strange look she got from an Elite whenever she bragged of being a Nirshaddun.
"I'm quite sure you heard me. And the armor of polished shadow, well, it's actually-"
"What was that fucker's name?" 
"According to your contact report, the Elite who told you of the Nirshaddun introduced himself as Tarshe Kandonom."
"I'm going to find that son of a bitch and tear his tongue out through his asshole!"
"The odds of encountering that Elite again-"
"Don't tell me the odds!" 
=== Five Years After That ===
Cassandra-A096 called in every favor she was owed to get PERUN assigned to this mission. Frankly, the target was hardly worth crushing with a team of Spartans. The Oathsworn of Duuvan Nizat was a small warrior order that was moving arms from who-cares-where to a minor power player in the Kirsaadian Reach. It was one of those rare conflicts where neither the UNSC nor the Swords of Sanghelios had a dog in the fight, save for a general dislike of arms smugglers.
Cassandra wanted this mission like nothing else, because Tarshe was one of the Oathsworn.
The shooting already started when the Pelican touched down at the pirate port. It was one of those turf wars that frequently erupt between rival bands of arms smugglers, and it looked like the Oathsworn were winning. That was good. It meant that PERUN was weapons free as soon as they cleared the Pelican, and Cassandra had a license to even those odds.
PERUN tore through one room after another, dropping aliens and barely stopping to secure evidence. Finally, when the team was temporarily stalled in a disused hangar, Cassandra saw her quarry. An Elite in red armor was ordering his troops into cover behind dust-covered service vehicles on the far side of the room. For a moment, their eyes locked together, and the Spartan saw Tarshe's mandibles widen in surprise as he somehow recognized her.
Tarshe fled. Cassandra fired a trio of shots from her shortened sniper rifle, but only one round hit before the Elite ducked through a door. With a scream, Cassandra broke cover and sprinted to follow.
On a clear field, an Elite had no chance of outrunning a Spartan III in MJOLNIR. This was not a clear field. There were turns and obstacles every which way, and Tarshe knew the territory. Worse, the Oathsworn apparently weren't the kind to shoot deserters who were fleeing battle, not when there was a Spartan to shoot instead. Cassandra moved fast and shot Tarshe's compatriots only when they got in her way, yet she was quickly forced to resort to her M6 sidearm to save ammunition. She shot, jumped, and sprinted to catch up, never daring to lose sight of that red-armored Elite.
The chase ended in another hangar, where an Oathsworn freighter with an open cargo bay was warming up its engines, just a few seconds shy of taking off. Tarshe crossed the tarmac in great bounding strides. Cassandra never broke stride, just slowed down a bit to keep her crosshairs zeroed on the alien's back.
CRACK!
The Elite's shields flared like a struck match.
CRACK!
The shields collapsed entirely. And Cassandra's sniper rifle locked open on an empty magazine.
Cursing, the Spartan dropped the mag and rammed a fresh one into the magazine well, fumbled, corrected the fumble in a split second, and felt the bolt slam home. But by then, Tarshe had already dove into the cargo bay and punched a control panel with his fist. A hard barrier of blue energy winked into existence, closing off the whole cargo ramp.
Still at a dead run, Cassandra dumped the whole magazine into the energy barrier, to no avail. She hit the barrier in a flying tackle to equally disappointing results, save that she smashed the scope of her rifle.
On the other side of the barrier, Tarshe was nearly doubled over trying to catch his breath. Cassandra hammered on the energy barrier with her fist until she caught the Elite's attention, and then she drew a combat knife.
"I found you once, Tarshe Kandonom," she said, clicking her radio over to the Q-BAND on the Covenant Battlenet. "I'll find you again. And when I do, I'm going to tear you a new asshole."
The Sangheili's mandibles split in a toothy grin. 
"Truly spoken like a demon of carnal pleasure," he retorted.
Cassandra-A096's banshee screech of frustration was lost in the roar of the freighter taking off.
=== Some Time After That ===
"So, it has come to this," Tarshe says, looking out the armored window. Bodark and Obadiah coolly return his gaze from the other side.
"Hell yeah," Cassandra says as she draws a knife. It is no mere combat knife. This one has serrations and hooks ground into the edge, the kind of blade you could intimidate a witness or skin a crocodile with. "You and I, we're going to have one Hell of a time."
Tarshe's mandibles twitch as he expends heroic levels of effort toward swallowing another smartass remark. Instead, he gauges her progress across the deck and he asks "How many years have you chased me across the stars? How many times have we clashed? And after all that, there is but one more thing I need to know."
Cassandra stops just short of him, and her eyes narrow to slits. "If it's another smart-assed remark, go ahead and say it. I'll just take it out on your hide."
"Cassandra, demoness warrior of the Yun-escee," Tarshe says as he takes off his helmet. He then drops to one knee, and pulls a gold ring out of a pouch. "Will you be my lawfully wedded wife?"
Cassandra.exe has stopped working.
Tarshe seizes the knife hand and tackles her. In the ensuing wrestle for the knife, Tarshe comes out on top, and Bodark and Obediah now have a hostage situation on their hands.
Cassandra spends most of the standoff in a leglock, and her screams of "This is not what it looks like!" are omitted from the after-action report.