Universe: Prime I guess? But has G1/IDW characters too.
Plot: when the war is in its most terrible moment, and Decepticons are winning, Iacon is the last city still in Autobot hands. But for how long?
Warning: robot gore.

Bots walked through the streets of the former greatest city of Cybertron. Thin younglings helped soldiers carrying things to build defenses, stumbling a bit sometimes. Their blue optics dim with hunger. In silence. They didn't have the strength to talk.
One yellow, blue and white mech was watching over them, his blue optics narrowed. Grumbling quietly about how his commander had sent them, an elite team, to watch over construction.

"Hey Seaspray. ' a voice called out, and the big mech turned to look at the owner of that familiar voice.
" Wheeljack. " Seaspray grumbled softly, " why aren't you at work?"
The white warrior just smirked. He unsheated one sword slowly just to clean it, speaking calmly:"Why don't we go off doing something else? Maybe toward those mines at the border? Bots are still fighting there, we could be much more useful than here just dragging stuff along."

Seaspray rolled his optics irritated at Wheeljack's words.
"Wheeljack you know Ultra Magnus sent us here to work." he muttered softly 'I don't want to lose my helm and I don't think you want either. "

The other bot scoffed.
" Who cares? " he asked" Magnus is off to that psychiatrist because Optimus sent him. He won't know a thing until we have won the battle and will bring him fresh energon supplies as an apology. "
Seaspray actually started thinking about it. It could be a good chance to replenish their dangerously low storages of energon. And after all, Iacon was not going to be attacked that day right? No Decepticon would be so stupid to enter that city, and a full attack was usually preceded by movements of the ground troops or the seekers. The cons were more focused on getting the energon, like they were.

"Alright." Seaspray sighed and commed the others, who were just eager to leave that boring duty to have some true action. A few minutes later the Wreckers left the city with a excited grin and weapons unsheated, ready for a fight.

Meanwhile, in the Autobot base of Iacon a large blue commander sat on a chair, grumbling softly as he looked at a small, elderly mech. Who was smiling at him with that gentleness that made him even more irritated. Ultra Magnus hated to be there, and having to talk about his feelings or things like that. Just because all the other soldiers did go it didn't mean he needed it. And that smile. That patience of the psychiatrist just waiting for a reply like he had nothing to do all day but listen to the story of his life. It truly made him wish he could just smack him against a wall. But he was an officer. And he wouldn't have started a fight with Rung, ever. He was an old mech. He had to be patient. So he started speaking quite coldly of his work.

"I fight, I kill, it is my job." he said icily "along with advising Optimus and leading troops. That's it. '
He realized he may sound a bit like a psychopath as he was showing no feelings or distinction between killing and advising. But he truly didn't want to tell how it felt to know his servos were stained of the energon of countless bots. It was a matter that concerned only him. He would never tell Rung. Or anyone. He just wished someone could understand it.
Rung was telling him something but he just had spaced off. He wished anything could interrupt this  torture. Anything.

He had just finished that thought, when a loud roar rose drowning Rung's gentle voice. The commander had frozen for half a second, not daring to turn, then slowly did so. He wished he hadn't. From the windows where they could usually see Iacon, they could only watch dense, dark smoke rising. Ultra Magnus jumped up immediately, frowning as he started getting comms from Optimus, asking a report from his Wreckers who were in the city. Worried sick, he left the office without looking back and commed Seaspray.
::Soldier report! What is the situation? :: he asked.
The voice of his right hand replied after a moment:: Everything is fine sir, why? ::

The commander felt his spark drop.
::Everything is fine?! :: he snarled ::I just saw Iacon blow up and you tell me everything is fine?! Are you even close to where you should be? ::
When only silence replied to him Magnus just stormed toward the main room, his optics blazing.

The yellow Wrecker had been gunning down the last few cons with a satisfied grin when he  received the comm. He paled horribly at Ultra Magnus' words and looked at his comrades who were cheering and making fun of the fleeing bots.
"We have to go back. Quickly." he ordered, earning a confused look from Hound and a snort from Wheeljack.
"You scared of Magnus?" the white mech laughed, but when he looked at Seaspray straight in the face his amused look disappeared. Reading the true fear and horror in his expression. All the bots stiffened scared at that look. Waiting for his words.

"Iacon was attacked."

When they arrived to the capitol, the smoke still filled the air. Where once there were high buildings, defenses, walls, there were only ruins. Seaspray approached the ruins slowly, blasters out. His optics went huge as he noticed something of a metallic, bright color somewhere under the  rubble. He started moving the heavy darkened metal to find what it was. When he did, his spark dropped, and he wished he hadn't.
A small red body was in front of him. His chassis smashed violently, his face almost unrecognizable because of the heavy pieces of the building falling on him.
The whole right side of the face almost melted other than smashed, because of the horrible heat released by the bomb, which traveled through the metal. His turned off right optic was almost invisible under the melted metal slowly dropping from his forehelm.
But the left part was maybe even worse. The most heavy rubble fell on that part. The metal didn't melt. It was  deeply lacerated, wires coming out of everywhere, his optic destroyed, a hole in its place.
Seaspray shuddered more as he realized the mechling was probably barely ten or twelve vorns. One of the kids helping bringing stuff to build defenses. The Wrecker closed his blue optics, before someone started approaching.
"Get up." a voice ordered sternly and Seaspray turned to face his huge commander standing in front of him. His gaze showing nothing like always. But really, the yellow Wrecker couldn't bring himself to get up. He didn't want to see the full extent of the destruction his decision had brought. He wasn't sensitive to what he did to the enemies, but causing this to younglings, to old bots, to sparklings was a terrible thing.
He was shocked when Ultra Magnus literally grabbed him and forced him up briskly.
"We need to go help the medics to look for survivors." he ordered harshly 'at least I think you all can do that. "
He then turned away without waiting for reply, starting going toward the center of the city. Seaspray shuddered, before following.
Maybe they could still save someone.

When the Cybertronian sun fell for the seventh time since the attack, and darkness covered their vision, the bots were still searching.
Ultra Magnus wasn't stopping. No survivors were found, the few who still vented when taken out of the ruins died either in their arms or on a makeshift berth, crying for agony. The commander though couldn't bring himself to comm his leader and say there were still no survivors. Optimus was trying to reassure the neutrals who had been in the base to talk during the attack. Leaving him to deal with the disaster his soldiers had let happen. But after days he couldn't bear it anymore. He went over to some of the youngest troops who were sent to help with the rescue. His frown deepened as some of them were throwing up energon and oil, shaking violently. His blue optics narrowed seeing their delicate frames, realizing they were little more than sparklings. He felt some pity, and looking at everyone else, he realized all this was useless. So much time had passed. Most of the bots were so tired, some were sobbing, many had sat down burying their helms in their knees. They would not find anyone.

"Let's go back to base." Ultra Magnus ordered, watching the bots slowly get up to follow, some relieved, some crying more. The commander couldn't bear the sight of their traumatized expressions and turned away, walking back to the base. Trying to erase from his processor the horrors he had seen during those long, pointless researches. Leaving behind, where once there was a huge city full of life, only death and destruction.