/1902 hours, April 22, 2552 (UNSC Military Calendar) / Cygnus System, New Jerusalem Theatre of Operations/
Kat-B320 ran with M6 in hand, the opposite arm cradling the MFDD tactical nuke like a large football. Lungs burning, vision bobbing, her legs miraculously continued to fly as she sprinted. As explosions shook the muddy soil, she glanced down long enough to input the code that would activate the MFDD's countdown. Five minutes to plant it onboard the CCS-class battle cruiser hovering above, blotting out the sun. Blue plasma fire whined by, but she didn't stop, didn't falter, couldn't afford to as she simply flicked he safety and let loose with the sidearm. Dirt thunked softly against her armor as a nearby detonation sent the brown clumps in every direction. A second explosion flung a Marine to the ground.
Kat passed Jorge, his heavy machine gun reports booming. Her feet continued to pound across the terrain, her own breathing becoming the only thing she heard. She saw Jun level his sniper's rifle and down a Covenant Unggoy too close to her path. Kat's M6 bucked several more times before clacking empty. Another few hundred meters and she was golden.
She heard the Banshee fighter before she saw it, but even then it was too late. As it zipped past with a thin sound not unlike a pot of boiling water, the green flash of its assault cannon momentarily blinded her, the expanding heat wave lifting her, sent her tumbling like a ragdoll. She landed with a sickening crunch on her arm, then rolled painfully onto her back, M6 and MFDD slipping from her fingers. In her peripheral she could see her arm was in an unnatural shape. Kat's HUD was shattered, display appearing fragmented, distorted. She couldn't move. The pain, it was too intense, air just barely managing to hiss into her lungs as she felt the sticky trickle of blood on her cheek. She was already pushing the clock as it was. Now… there was no hope of getting it onboard and getting herself off.
Kat willed her fingers to work, needed to type in the deactivation code. She was the only one who knew it. The fingers didn't even twitch in response. The entire arm refused to work.
She saw Thom-B293 standing above her, knew what he intended to do even as he bent to snatch up the tactical nuke. She tried to scream for him to stop, to tell him the codes, but her lips barely mouthed the words, no air to resonate in her vocal cords.
For another brief moment they stared at each other, visored gazes meeting as a tear rolled from Kat's eye to mingle with her blood and sweat. Thom's shoulders visibly slumped under the weight of his duty, then he stood ramrod straight as he activated his thruster pack and launched skyward.
It was her fault, she had planned this op. She felt she had just cost her brother in arms his life.
Thom stood overlooking the troop bay, the MFDD counter plunging downward toward 0:00. He took a breath, steeling himself for what he was about to do. One last hurrah, he would go out with a 63 kilojoule bang. As the device's chirped warning intensified and became a solid squeal, Thom threw the nuke with all his strength towards the center of the gigantic chamber.
Kat watched, still immobile as orange gouts of flame blossomed inside the cruiser's shield. Then the blue shield shimmered, contorted, and dissolved as the Covenant ship became one big fireball. Thom had finished Kat's mission. Tears streaked the black grime on her cheeks as she closed her eyes and slipped into unconciousness.