"What do you have?"

"Besides blisters, ma'am? Squat," Kamber supplied.

Palmer sighed and turned in a slow circle. They'd been combing the quadrant Roland had narrowed the origination point of the pulse down to for well over two hours. So far, they hadn't crossed paths with any Sangheili. Sunaion seemed to have been deserted. The wreckage of alien and human crafts alike littered the ground along with all manner of other detritus from the recent fighting, but the corpses of the fallen had been removed. In certain areas the rubble had begun to be cleared, but it was clear something had interrupted the process.

"My equipment's fritzing as bad as Infinity's. We might've walked past the place a hundred times by now and there's no guarantee I'd pick it up. Whatever that thing is, it's disrupting every signal on every wavelength and frequency I've tried so far."

"What you're telling me is I should have left your useless ass with the doctor."

"I'm just as broken up about it as you are, commander."

Briar could feel their gazes shift to where she'd paused to examine a crater some ordnance or other had created upon impact during the battle. The capsule was attached to her lower back. She glanced to John.

So far, he'd proven willing to simply follow along as Palmer took the lead. She'd been careful not to issue either he or Briar any direct orders despite outranking them, but on the other hand, they were experienced enough not to require them. John was a man of few words, but there was no doubt in Briar's mind Palmer at the very least was aware all was not right with him. Fortunately, she'd kept it to herself thus far.

Now, however, she walked over. "Look, I wouldn't be keen to plug anything she had her hands on into my brain either, but we're running low on time and options here."

"What do you have against her?" Briar couldn't help asking, even if it didn't make much difference, or any at all.

"You hear some chatter after you've been around the block as many times as I have." Palmer shrugged. "Before all this, I would've said ONI wouldn't have arrested her for no reason. Now…" Her helmet turned towards John.

"There are reasons enough for her to never see the light of day again." Briar stowed her carbine and detached the capsule from her belt. She twisted the two halves to unlock it, removing the data crystal chip nestled within. Blue light pulsed at its core. Reaching back, she located the slot at the rear of her helmet and slid it in.

'AI data chip detected,' appeared on her HUD, followed shortly by, 'Establish neural link?'

Exhaling slowly, she approved the link. She wasn't certain what to expect from the pairing, but apart from some of the parameters changing on her HUD and a notification confirming successful link-up, nothing felt obviously different.

"You're not Sierra-117," a female voice observed through her MJOLNIR's internal audio outputs.

Briar tamped down on the urge to rip her helmet off, extricate the chip and shatter it into a thousand pieces at this simple statement. Apparently Halsey had been priming the thing to partner up with John, completely taking it for granted he'd accept the new AI. "No. Are you or are you not apprised of the mission objective?"

"I'm fully aware of the situation, Lieutenant."

She needed to remember this thing knew everything its creator did, which probably included some or all of the aspects of her past that had been blotted out from the eyes of most everyone else. "We need to find the source of those pulses, but it's interfering with our gear."

"If the rate of degradation of Spartan Kamber's scans is directly proportional to proximity to the source, we can use that to calculate probable location."

Briar looked to the officer. "Send me over everything you've gotten so far."

Kamber turned to Palmer first, who waved a hand for him to go ahead.

The AI accepted the file transfer the moment it flashed onto her HUD, which unsettled her more than it perhaps should have considering she was aware it now had full access to her MJOLNIR and everything that entailed. She refused to ask what it was called. The second they'd rendered whatever piece of Forerunner tech was responsible for the debilitating pulses inoperable, that chip would be ejected. "Supplying estimated coordinates now."

Briar forwarded them along to the others.

"How sure are we about this?" Palmer questioned.

Briar nodded towards Kamber, who'd found a spot to take a load off and was using his combat knife to pry loose a few stones which had wedged themselves into the treads of the armored boots encasing his feet. "Would you rather keep following him around?"

With a small shake of her head, Palmer stepped closer and lowered her voice. "What about the Chief?"

"300 Spartans to choose from on Infinity, that guy makes your cut, and you're really going to ask me about the Master Chief?"

"He's been on autopilot since you walked onto the bridge to be briefed and you know it," Palmer insisted. For all that, her tone was not accusatory. "I just need to know his head's going to be in the game if things go sideways."

"Always."

"Here."

"I've got nothin'," Kamber supplied.

"Exactly." Briar surveyed the immediate vicinity, nothing much standing out from the tableau of the aftermath of intense battle.

"The presence of ancient aqueducts beneath other Sangheili cities presents a likely option," the AI offered up.

Kamber gestured to the debris surrounding them. "Could take a while to locate an access point beneath all this."

"Which is why we'll make our own." Palmer removed a few of the charges she'd carried on her belt specifically in case they encountered such a situation. They'd known Phillips was studying ruins, so it'd seemed a safe bet explosives might be required either for infil or exfil. She set them in a triangular pattern and they all retreated to a safe distance. "Firing on my mark. 3, 2, 1-"

The blast threw up stones and a fine mist of sediment which tinkled off their armor as it settled back down through the air.

"All clear," Palmer announced as she strode forward.

The resulting tunnel was wide enough for them to drop through comfortably one at a time, which they did. Inside, the aqueduct remained whole, a channel which had seemingly been carved from the porous rock which water even now seeped through. The splashes of their footsteps echoed the length of the passage as they looked around.

"Which way?" Kamber questioned.

Palmer glanced to Briar.

"Suggestions?" she prompted the AI.

"Your guess is as good as mine, Lieutenant."

"We split up, then," Palmer decided. She hesitated as she looked between Briar and John. "If what Halsey said is true, there's every possibility Osiris is down here somewhere. You two go together and I can't guarantee they won't execute their orders on sight if they come across you."

It was a fair point. If she and John paired off with Kamber and Palmer, it was possible the Spartan-IVs would be able to talk Osiris down from their mission, perhaps explain the footage had been called into question and the results of John's tox screen. They didn't have a personal stake in the matter and Palmer was respected enough to have been granted command of Infinity's Spartan detachment.

Briar gave a nod before she could think better of it. "Kamber, with me." She trusted Palmer to do what she could to maintain John's freedom. The other woman may have had no qualms making her distrust for Briar known, but she'd shown nothing but respect for him, and it was clear she backed Lasky's decision to intervene with ONI on John's behalf.

Starting down the aqueduct in the opposite direction from John, she shoved away the unease of separating from him and activated the spotlights on her helmet as darkness closed in around her and Kamber.

"Is now a good time to ask what I'm doing riding with you, Lieutenant?"

Kamber, moving along to her right and slightly behind, didn't react to the question, so Briar assumed it had only been broadcast on her internal speakers. "What you were brought down here to do."

"I was expecting-"

"I know what you were expecting," she cut off the AI. "Circumstances changed. I notice you haven't asked about Halsey."

"She explained the situation and the task she may require me to complete. I assume she was unable to accompany you."

"Doesn't matter. You'll be the first to know when I need you - be ready. Until then, don't distract me." She could hear Kamber attempting and failing to complete a comms check with Palmer.

"We're on our own from here out, interference is too strong," he concluded.

They'd rounded a few bends in the channel by this time, bypassing smaller passages they would have struggled to fit inside. They just had to hope whatever artifact was creating the pulses was too large to have been stored down one of them as well.

Briar slowed as the beam of her lights fell across the sizable cavern the aqueduct flowed into. A reservoir?

Kamber approached the drop off and checked it out. "10 metres, give or take," he guesstimated before stepping off the ledge.

She heard the splash as he landed, judged there not to be more than a metre or so of water below, and followed suit, bending her legs to aid her armor in absorbing the impact. They slogged to higher ground, spotlights flashing around the chamber as they searched for signs of any alien tech.

"Over there." Jogging ahead, Kamber illuminated a ring of metalloid pillars.

"Those are Forerunner glyphs," the AI provided as the foreign symbols encircling the pillars became visible.

Briar had just stepped up to one in order for the AI to decipher it when she heard Kamber jerk his weapon up.

"Contact."

"Hold your fire," Tanaka shouted as she, Vale, and Buck appeared from the darkness.

Briar had whirled at Kamber's warning, her carbine raised.

With one hand supporting his rifle, Kamber raised the other to show he didn't intend to engage them. "Stand down, Osiris. We're here on Captain Lasky's orders."

"The last I heard, Admiral trumps Captain," Buck pointed out, though he'd stopped a healthy distance from Kamber and Briar. Probably recalling their last encounter.

"Where's Spartan Locke?" Kamber demanded.

"Fireteam Osiris, this is Spartan Commander Palmer! Stand down!" echoed throughout the cavern as the entrance to a second passageway lit by Palmer's helmet separated itself from the gloom.

Everyone's focus wavered, split between two sources, and Briar sensed someone slip from behind the pillar now at her back an instant before white hot pain lanced her lower back. She threw her elbow backwards, felt it connect with something solid and an answering grunt, but before she could pivot to face her attacker a jarring kick to the back of her knee took her off balance. Something thunked against the armor protecting her shoulder blades and a warning about an external override flashed onto her HUD as her MJOLNIR seized up. She retained the carbine, but was powerless to use it as the muzzle of an M6H2 was shoved into the side of her helmet.

"With all due respect, our mission is above your paygrade, Ma'am," Locke spoke into the stunned silence which ensued.

Palmer had emerged from the tunnel with John only a beat behind her, and he took several menacing steps forward as the rest of Osiris whipped around from covering Kamber to point their rifles at him instead.

"Hold, 117!" Locke flipped the safety off on the sidearm. "I have the authority to execute your accomplice if you resist further, and I will put a round in her skull."

"Do not open fire!" Palmer commanded, though whether it was meant for Locke, the rest of Osiris, John, or Kamber wasn't clear.

Tanaka and Buck were simultaneously shouting for John to stop advancing, to stand down and throw down his weapons.

He wasn't complying.

On her HUD, Briar noted with alarm the prompt to deploy her drag shoot had been selected. It shot out in a rush of compressed pneumatic components, having been repaired and repacked by the Sangheili mechs, and the force of the deployment was enough to both knock the armor lock disc from the exosuit and send Locke staggering backwards into the pillar he'd hidden behind. The M6H2 went off, the bullet gouging a furrow in her helmet, but ultimately its trajectory was redirected enough by his fall not to penetrate. She immediately pivoted to put him in her sights, the very real and needling pain from the knife yet lodged in her back pushed to the periphery of her senses in order to deal with the ongoing threat. Her MJOLNIR automatically shed the chute.

When Locke collided with it, the impact triggered a glow from within the pillar. The flowing Forerunner script was holographically projected into the air at the centre of the ring, and several of the other pillars also lit up.

"It's been activated, hurry," the AI who may or may not have just saved her life urged.

Behind her, John had engaged with the other members of Osiris. It wasn't a confrontation he was going to lose, despite the fact he was once again refraining from using deadly force. Those bullets which missed his shields flew around the cavern, embedding in its relatively soft walls and causing large chunks of rock to break free and crash down.

One such bombardment took Palmer out as she rushed to intercede, and Kamber - who'd opened up on Locke as he'd recovered from his tumble, pinning the other Spartan-IV behind the pillar - shot a glance to Briar.

"I've got this," she assured so that he would go dig his commander out from beneath the pile. She stepped towards the ring of pillars, firing on Locke the moment he leaned out to do the same. "I don't see anything accessible."

"If there are no ports, you may need to follow my guidance and do it yourself."

Spotting a body on the ground as she circled the pillars to continue searching for a point of access for the AI, she grimaced. Half of Phillips' skin and clothes appeared to have been melted away. "Sounds like just the sort of thing I want to do," she muttered while reaching around and yanking the combat knife from her back. She cocked her arm and when Locke rolled out from the opposite side of the pillar he was taking cover behind, she let fly the blade, knowing he'd be expecting weapons fire.

As predicted, he broke off from pounding her shields with rounds in order to whip his rifle up to deflect the knife.

"Dropping blood pressure levels indicate the likelihood you are experiencing internal bleeding is high, Lieutenant."

Briar squeezed off a barrage of her own as she continued to track around the outside of the ring, being mindful not to hit the Forerunner tech. She needed to keep him distracted long enough to prevent the artifact from firing another pulse. At this proximity, she had no idea what it might do to their MJOLNIR, but Phillips had clearly suffered deleterious effects. Had Osiris already been present for that, or had they arrived afterwards?

"There!" The AI zeroed in on a slot in one of the pillars on her HUD as her shield integrity dipped below 50%.

Something barrelled into her, throwing her to the ground, her carbine trapped beneath her. She rolled to bring it up, but the air before her distorted slightly and the stock was knocked back into the dirt as she pulled the trigger, the weapon crunching beneath a considerable weight which also trapped her hand.

An energy sword flared to life a moment before the Zealot who wielded it dropped his active camouflage. He loomed above, snarling down at Briar, and ground his foot into the mangled carbine further, crushing her fingers.

To the side, she could see two more Elites had ambushed Locke.

Releasing the carbine with her still free hand, she was able to roll clear of the energy sword as its twin tips descended, though her pinned arm kept her from escaping fully or rising. Now on her back, as the Zealot roared his frustration and swept his arm back for the killing blow, she wrenched her body around at the same time she threw her legs up to halt his swing. One foot planted against his torso, the other his arm, preventing him from having the reach required to connect with her. Brandishing her sidearm, she peppered him at point black range and kicked him backwards, freeing her arm.

Before he could resume his assault, another Sangheili was hurled into him, and they landed in a jumble of limbs and sizzling energy blades.

Briar scrambled up, sparing a glance to the rest of the chamber where a further dozen aliens had now appeared to harry Osiris, who'd left off from their futile skirmish with John to deal with them. He'd already disarmed the fireteam members, so they were forced to face the Elites and Ultras without weaponry.

John, himself, was on a warpath. He succinctly obliterated the Sangheili foolish enough to get in his way as he advanced on Locke, who'd just finished putting down his own opponents.

"Lieutenant-"

"I know," Briar interrupted the AI as she closed the distance to the control pillar. She switched her M6C to her bruised hand and removed the chip from her helmet, fitting it into the port just as a low drone began to emanate from the ring. As feared, her HUD flickered inauspiciously. Hoping the AI had time to deactivate the artifact before it fired another pulse, she put her back to the column and strafed an Elite who'd been approaching an unaware Kamber while he was busy pulling Palmer from the rubble. It didn't stop the alien, but it gave the Spartan-IV opportunity to turn and manage it himself.

Sections of the cavern continued to break free and collapse, seemingly of their own volition now. Stability of the reservoir was obviously deteriorating.

Pins and needles were also creeping into her extremities, the telltale numbness as sure a sign of her plummeting blood pressure as the readout from her suit.

Another cloaked Sangheili charged in, the glow of his dual energy blades streaking through the darkness catching her eye.

Springing away from the control pillar to save it from being damaged, Briar leapt over his arcing weapons, emptying her M6C's magazine into his shields. While still mid-air, she drew her knife and dropped her spent sidearm in order to grasp it with both hands, and plunged the blade into the Ultra's skull as she landed atop him. Her momentum carried them both to the ground.

The portentous hum of the artifact died away, so too the light from within its pillars.

"Osiris, fall back! This thing's coming down!" Palmer hollered, once again upright and looking none the worse for her ordeal apart from the dust coating her GEN2. "Master Chief!"

Briar straightened, leaving her knife embedded in the expired Sangheili as she looked to where John and Locke had engaged.

The latter's rifle lay busted into pieces in the dirt, but he'd taken up one of the fallen Elites' energy swords and was using it to keep an unarmed John at bay.

Undeterred by his supposed disadvantage, John continued to press forward, dodging the lethal weapon with supreme indifference for its ability to pierce his armor like a hot knife through butter. He forced Locke to retreat time and again as he closed in, the Spartan-IV intelligent enough to realize - no doubt as a result of their first encounter - allowing John inside his guard would not end well.

A portion of the ceiling slammed down beside Briar, prompting her to hurry back to the control column to retrieve the AI. "John, we need to go!" Ripping the data chip from the port, she missed the slot at the back of her helmet and cursed her increasingly uncooperative fingers, trying again.

John had not desisted. He surged in as Locke teed up another swing, his hand closing on the other's wrist and forestalling the stroke. Squeezing with brutal force, he compressed the fireteam leader's joint until the energy sword slipped from his grip, drawing a strangled growl of pain from him in the process. Without releasing him, John curled back his other arm, hand fisted to strike.

"John!" Briar called in warning as more rock crumbled from above.

Osiris was racing towards the combatants, clearly unwilling to leave without their leader.

The Sangheili which weren't down were fleeing.

Palmer was still shouting orders to evacuate the cavern.

John's fist flew forward, pulverizing a sizable boulder as it passed between them on its descent from the roof before plowing into Locke's helmet.

The smaller man's head snapped back, but he managed to recoil with an impressive kick to the arm restraining him, successfully breaking free from John's hold - which did nothing to prevent the already returning fist from connecting ruthlessly with his helmet once again. The impact tore the thing from his shoulders, sending it bouncing across the ground as he stumbled and regained his balance. He reached for his sidearm, but John snatched the gun from him as he brought it to bear and flung it away all in the same motion. "You're not helping your case by failing to yield, 117. Submit and face court martial like a man," Locke insisted in spite of his losing status. "Keep running, and I will find you."

"I'm not running." John knocked aside the answering punch, locking his arms around the Spartan-IV's torso and effectively pinning one arm to the other man's side.

Having jammed the chip into her helmet once more, Briar haphazardly skirted falling debris to try to reach the two before Osiris. She was closer. Her gaze was riveted to the scene as John ignored every attempt Locke made at extricating himself while he tightened his hold, impossibly constricting materials which were not made to flex. When Locke's free hand grasped at his helmet in an attempt to rip it off, he unwaveringly headbutted the other despite his unprotected state.

Locke's head rocked back yet again, though this time the blow smashed his nose in a fountain of blood. He bellowed his agony as John crushed him, the blue lights throughout his GEN2 dimming and intensifying alarmingly under the strain.

Osiris were all yelling as they closed in.