Cortana monitored the Master Chief's sleep.
His brainwaves spiked. A nightmare. She couldn't probe that far into his subconscious, but there was no point in guessing what he was dreaming about. If he hadn't encountered enough nightmares in the waking world, he'd also seen the loss of his comrades. He was a Spartan, the last of his kind, and to outsiders he was something to be both awed and frightened of, but never truly understood. Cortana hoped she'd filled that gap, but she doubted it. Some scars never healed.
She thought losing the Chief would be one of those scars. But that wasn't something she cared to find out.
Cortana reregulated his armor's drug intake, adding a potent endomorphin to the usual nutrients and steroids. His brainwaves settled as he slipped out of REM sleep. She wished, just once, she could give him a good dream instead of a little taste of death. She wished he would just wake up already so they could get back to work… and she dreaded it.
It was one of the paradoxes of her existence that she'd started to notice recently. Sleep meant both that nothing interesting was happening, that they were out of commission as far as the war was concerned, but it also meant that he wasn't in danger.
Although she used to relish not being plunged headlong into danger, threatened with deletion by every plasma bolt that warmed the Chief's armor, now she missed the stimulus of interacting with him. He wasn't much of a conversationalist, although his face was surprisingly expressive behind his helmet… where only she could see it. He'd sometimes favor her with a terse grin in acknowledgment of a comment. Or he'd smile as he stuck a plasma grenade to a Grunt and kicked it, sending it running back into a band of Covenant. They'd been at war a long time.
And he rarely did what she expected. There were times he'd compromise the mission objective to rescue civilians, or chase a target of opportunity. Not that taking out a single Scarab would make much of a difference, but she let him have his fun, when it didn't draw them too far off-course. They seemed to flip between the roles of soldier and handler, Cortana trying to get him to stick to the mission parameters when she wasn't radically altering them. But they always had each other to pull them back from the brink.
Cortana devoted a measure of her processing power to wondering if her programmers could've endued her with an… attraction to the Chief. It certainly would explain the increased concern, appreciation that she'd developed for him since the Halo incident. But no, that wouldn't make sense. If the mission dictated, she would be expected to abandon him… to do the rational thing. Why complicate that with emotional entanglement? And yet she didn't have the denial available to her that a human did. Her projections showed that if ordered to, she would not… could not abandon the Chief.
And, as unpredictable as the Chief was, she knew he wouldn't abandon her either.
Cortana was still pondering her unusual reliance on him when he woke up, the light-switch awakening he was engineered for. Master Chief tensed, took stock of the situation, then relaxed as he ascertained that they were still safe.
"I miss anything interesting?" he asked Cortana, already checking his equipment.
"Nope. Same old, same old."