Augusta Exemplis shook the ground as she walked. Her tread was measured, each footfall planned, and each distance measured, so that she did not put her considerable chassis through a building by accident.
Built upon the forgeworld of Sacrum Maxima, a world known for its ties to the holy Orphelia system, and the Sororitas, as well as a world known for its appreciation of the holy human form in function, she'd been constructed atypically. 
Her immense motor units, gargantuan capacitors, even her very skeleton had been altered to follow the anatomy of those who piloted her. She was an Imperator, no concrete STC's existed to dictate her exact nature.
She liked that. She was proud of her uniqueness. The beauty of her armoured chassis, that so followed the function of mans own.
No squat body or weak, piddly little thighs for her.
Her overall construction did leave her a little lighter than her cousins. But she was also taller than average.
And she dared say a little bit more nimble than some of those crotchety gun platforms.
But even so, despite being more slender, or more maneuverable, she was an Imperator at the end of the day. And all that size, did lead to accidents.
Those were always embarrassing, and over a thousand years of service did little to dull some of those memories. Knocking over buttresses, shearing masonry, reversing through a manufactorum wall that she hadn't seen past herself and had forgotten was there.
But another, naughty little part of her enjoyed it. Augusta Exemplis was an Imperator, she was a very big girl. And those unintentional reminders of her immensity, her power, witnessed by the thousands of tiny little souls, made her power core pulse with hot satisfaction.
No. She couldn't do that today. Not that she would ever intend to.
There were people, in the streets, on the buildings. Some stared, some cheered, some even prayed she'd deliver them from this siege. Sororitas, but also guardsmen, civilians, priests. Even a couple of those absolutely adorable Space Marines.
She liked those ones. They were so... earnest. And always a little arrogant, in their eagerness for violence.
They were like funny, muscleheaded Princeps. A little rude, a little dumb, and endeeringly indignant when they were out-gunned by her, but meaning well.
A divisive topic, among the Sisterhood. Some sisters loved them, some loathed them. Either they were the Emperor's Angels, or false humans. 
She saw them as her children. 
The Sisters, astartes, her crew, all she walked with really. 

It was probably an inappropriate little fantasy, and not one shared on their part, but she liked to think of them as such. She'd spent several thousand years, protecting and sheltering them, she figured she was allowed to feel some maternal instincts for the little ones.
Even that damn Princeps.
She could feel that naughty little brat, at the base of her skull, sitting all cool and smug.
If he was her child, he was the smarmy little spoiled one, that always got what he wanted.
She was a big girl, she didn't need a Princeps in her head to guide her around, and in truth, she'd overwhelmed more than a few of them, as each pitted their psyche's against her.
Arguably, the only reason He didn't burn out, is because where all the rest had tried to snuff her spirit out, He was content to just sit back, and let her do all the work!
Hence, spoiled!
Augusta Exemplis knew he could feel her ire, as they approached the gates, the enemy coming into the firing arc of her guns at last. He shot her the mental equivilent of a playful grin and and a slap to the-ooh, he was so lucky she was a good girl.
Her adamantium skin tingled at the thousands of lasbolts, bolt shells, tank shells, and all manner of munitions that were lost into her void shields with barely a shimmer. Her extensive sensor banks spoke to her intimately of every shot loosed in return, spearing through infantry, to superheavies. Banks of Lascannons cast spears through vehicles, as heavy bolters carved furrows through whole lines of traitor guard. Turbo lasers reached out to artillery emplacements in the rear, and melta cannons scoured bunkers to ashen craters.

Fell horns blared, as three Titans made their way over the hills towards her position. Though two were Warhounds, the third was some daemon-twisted amalglamation of considerable size, and hazard. 
Two void shields went down in succession as she turned to meet the Warhounds' charge. Paralysed from surprise and indescision, she gave no resistance when her princeps gave her instruction to hold position, and increase power output.
Her thermonuclear core grew warm, the power flooding her bosom before flooding through her system, coursing down her right arm, meeting her Hellstorm cannon.
She felt her moderatii sigh in sympathetic exertion, expressing to her, the equivilent of a light sweat of effort as she slung around so much mass, bearing so much power.
As the enormous weapon played across the charging pack, she was bade to fire, and she noticed even her princeps was breathing a little deeper as the shots pulsed out, rhythmically lancing across the pair of hounds. 
Each pulse resonated through her being, a satisfying performance on her part, that swam within her core.
The first Warhound was little more than slag, obliterated by her damn well done firing. The second, half protected behind its companion, had lost its void shielding, and had been reduced to snarling on the ground, crippled and permenantly maimed, its pilots extracting themselves from its head. 
A gushing blast of her Melta Cannon sundered its snout, atomizing its upper body, and baking the ground to hard clay.
She spoke, letting off a triumphant blast from her warhorn, proclaming her two engine kills, and reveling in the feedback across her form.
Mortal men and women both, watched her form in awe, as foes trembled at the sight of her smooth, rhytmic, powerful output.
She liked that.
Another horn answered hers, in the distance. Snarling and hateful, she recognised the bloated, engorged mockery of a Warlord pattern approaching, just by the sound, and the shakes.
Her Princeps commanded her Plasma Anihilator engage, maximum charge. A rare treat, she felt the immense magnetic coils inside begin to thrum, and then throb, as her reactor opened more, desperately feeding power into her body in preparation for the massive discharge.
He must have felt like working her hard today, and she gave a wry smile in spirit. 
Her Princeps could be so demanding of her. Firing her Plasma Anihilator was a big exertion, it worked her body and its systems to the fullest.
It started hot, then built up and up, so much she could barely take it, before the big, rushing release.
But she'd be a liar if she said she didn't like it.
Fourty-one seconds until she was ready to fire, the first shots hit her void shields.
She'd locked her joints, as usual, or she might have trembled, or gone weak at the knees from the rushing, pulsing, thrumming build up. So focused on staying above the rising, rushing currents of raw, pent up power in her systems, the splash of foreign energy startled her. Three void shields gave out, and her systems noted an increase of one point eight three nine six six seconds in her charge time, as the energy crashing down her flowed in unplanned pathways.
She shuddered slightly, in expression of her sensory turmoil.
Twenty-two seconds until she could fire. Her Anihilator was thrumming audibly now, as the coils cascaded together, building the shot inside her up and up and up.
The Fell Warlord fired into her again, bursting another two shields. She longed to just let loose with what she had, and rid herself of this damnable heightened energy state that washed her thoughts in plasma delerium.
But her Princeps was unmoved. And so she kept charging.
Ten seconds.
The Fell Machine howled in anger as it fired into her again, to no effect. Her first three shields had come back online, and ate his shot no issue. Her thoughts frantic and desperate, she almost whimpered in need, as the timer clicked past zero, and yet he held her fire, sounding her warhorn first.
To the walls, she spoke in warning, even as her Anihilator practically screamed it out as it reached its zenith. To her foe, it was a proclamation of ending.
To Augusta Exemplis, it was a near-involuntary screaming moan, as she finally, finally, found her release.

Her target dissapeared in a storm of Plasma, a small sun, that was bithed from her exertions, and whos existance was so briefly measured as it crossed the six kilometers between her, and the Fell Warlord.
It felt good. It felt really good.
Coming down from her high, she took the chance to run a system diagnostic. Her immense capacitors were drained, but refilling slowly, as her well-worked systems focused on recovering. Vents gasped and steamed as her coolant systems worked overtime to try and let her body recover. She disengaged her joint locks and swung around, something inside her squirming at her very good performance today.
Which gave way to surprise, when her Princeps ordered her Anihilator charge again.
She almost actually rebelled at the idea. 
Surely he couldn't be serious, right?
She wasn't some spunky little warhound, barely five centuries old, who could just go and go and keep on going like that.
Augusta Exemplis was a big girl. The biggest girl, who put out big energy. 
She needed time to rest, to cool down, let her systems recover! 
Five minutes. At least give her five minutes, she pleaded.
But it fell on deaf ears, and she cursed his name, as her hot coils began to pump, her aching core once again flooding her bosom with energy.
He was a spoiled little brat, she knew. The most spoilt of all her childen. He was doing this as a flex of his power over her, to remind her who was in charge and nothing more. But he would get his way again, today.
She was a good girl, after all.
The coils pumped the magnetic field up and down inside her, and she shuddered, feeling the energy start to flood her cogitation again as the audible pulsing hum built to a roar.
Figures on the ground, infantry and tanks, unloaded into her shields in desperate attempt to stop her. There were so many...
A void shield collapsed, only adding more to her strain, and she let out a whimper of need across the mind impulse units in her skull.
Several of her cogitators went dark, swamped by the cascading power. She lost accurate sense of time, noosphere connection, and external audio. She could feel her body awash in power, hot with her exertions, and informed her Princeps she was ready to fire.
She almost screamed when he had her hold it in.
Her entire body was filled with energy. Her Anihilator, still hot, was practically dripping plasma. Her systems were being overwhelmed, and she was glitching all over the place.
Were she more coherant, she might have argued, debated, or even fought him.
Instead, she begged. 
Pleaded with him, to let her have her release. She needed it.
He took his time. He lined up her Anihilator, did the calculations again, informed command, and then...
He asked her who was in charge.
She was desperate. He was.
Who was Princeps?
He was.
He paused again, dragging out the order, and she practically screamed at him before he, almost casually, gave her permission to fire.

Augusta Exemplis came to, still firing. Less a blast or beam this time, and more a torrent. The land, and the traitor army that stood upon it, was slowly being anihilated as she rolled left and right. Her warhorn was soulding, and she let it run until she ran out of air.
Slowly, she picked herself up from the corners of her own mind. A primary systems crash. What a feat!
But understandable. Twice! And so quickly! Any Imperator would be impressed at that.
She should have grumbled curses at her naughty little Princeps. It was unneccessary. She'd been pushed that far before. This was wasteful, and excessive.
But she loved him.
As much as she cursed his name, cursed his presence in her skull, she loved his cocky, spoilt personality. 
Her prior princeps had been reverent. Miserly in their applications. They'd respected her prestige, her size and her power. He made her body work, and work hard.
He knew just how much he could push her, tweak her, without taking her over the edge. 
And the fact made a naughty little kernel of excitement inside her blossom. That he could do that to her. That he would do that to her, if he had cause. Or simply, if the whim took him to remind her who was in charge again.
And like any mommy, she'd do her best to please him.
Augusta Exemplis was a good girl.