Spoilers: obviously content from the games including the Ending.
For the most part this will follow ME lore, just adding and adapting.
Rated M since i don't want to limit what i can and can't do as the story progresses.
One for All
They crawled through the maintenance ducts of the ship. We must reach the docking area, they had concluded before they had left the people in the labs behind.
The Creator had given them a data drive and made them promise to deliver it to Normandy. "Whatever happens promise me to deliver the disk to the Normandy." The creator had told them.
Then the creator had left them and had gone to help the Humans defend the labs.
They had been fortunate the designated enemy was not using the maintenance shafts to move through the ship. But sensors showed movement in the docking area, they would need to find guns in order to defend themselves. They where the only platform that was in a working condition for now. The creator had uploaded data about another platform. The one that designated himself as Legion the one that had achieved true self awareness.
The creator had wanted them to understand what Legion had been and what he sacrificed. Now it was up to them to save their people and bring them back. So Legions sacrifice would mean something. They had understood that the creator had now risked her life to give them a chance to escape. They would help her if they could.
When they neared the docking bay, they saw two shuttles landing and starting to fight the creators enemies. They concluded that to help them would mean raising the probability of mission success. They leaped an enemy from behind and took his gun. They would provide cover for the temporary allies.
"Garrus take out those engineers, EDI get me control of the doors." Kaidan leaped to action The mercs weren't really organized, just there where so damn many and they had secured the area.
"Kaidan, two behind those crates." James shouted.
"Make that one eh no none... What the who took those out?" Garrus scoped out the area.
"There that one is setting up turrets take him down now." Kaidan ordered, But before anyone could even fire a single shot the engineer dropped dead.
"What the..."
When they had cleared the area a loud bang made them turn around. Guns raised they looked towards the direction of the sound.
"Alenko Major, Normandy designation allies. We are Geth, Creator Tali'zorah told us to go to Normandy." The geth spoke and lowered it's gun.
"I'll be damned, she is alright then?" Kaidan lowered his gun.
"Creator Tali'zorah Was last seen defending the labs. We where told to bring this data drive to Normandy."
"Go to the left shuttle EDI is in there. If you can tell me anything about the attack that might be helpful."
"We shall relay any information to the Normandy AI. But i... We must go and see if we can be of assistance to creator Tali'zorah." The geth ran off to the shuttle.
"Okay people double time it, we must stop this ASAP!" Kaidan said, in his time with Shepard he had picked up on a few things. First no time to loose, second no time to play nice on the battlefield. Those lessons started to get useful now that everyone had looked at him to take over.
They made their way through the floors of the ship. Cleaning out the mercs trying to stop them and waiting for EDI to bypass the security lockdowns.
"Kaidan, Charles is making his way to the labs through the maintenance shafts. His Intel gave me enough to take over the security feeds." EDI informed them over the communications channel.
"What who is Charles? And where are the mercs, we haven't seen any on this floor."
"Charles de Batz-Castelmore d'Artagnan, I assumed our new Geth friend required a name, after he said he is just one fighting for all, I thought human literature was a good source to give him a name."
"EDI no time for chitchat, a simple 'I gave the Geth a name' would have been enough so where is the enemy?"
"Split in two groups one group is fighting their way to the council. The commands seem to come from the labs however. Tali seems to resist them from breaking in. Also Kaidan sensors indicate Admiral Hacket is with the council."
"Shit, Okay tell the geth.. eh Charles to meet me in the Labs. Garrus, James give the council some fire assistance and draw the enemy away from their position."
Garrus nodded wen they split up.
Kaidan ran to the labs, if he could get to the leader of the mercs the others could save the council. Not that the council was helpless against a few mercs, just he wanted answers and if he could get to the leader of this bunch there might be some.
Wen he was near the hallway where the labs where located Kaidan checked his weapons. "Charles what's your position?" He asked over the com.
"We should reach the central laboratory in 2 minutes. Major Alenko there are 12 armed designated enemies north of your position. We suggest you wait for us to reach the ventilation shaft otherwise your survival chances would be only 12,5%"
Yeah, always nice to have someone remind you of how low your chances are. "Okay Charles but I would bet my chances would be closer to 13%"
"Negative, we have already accounted for what Legion called the Garrus paradox."
"Well just say wen. I'm ready, can see three from my position." Kaidan waited, annoyed by how low the geth said his chances where. Really they where so depressing.
"Alenko Major, we are in position as soon as you make your move we will take out the ones furthest away from you. It should distract them."
"Okay Charles, here goes 13%."
"45% now that we are here."
Kaidan snorted, really the geth thought he was worth 32% of Kaidans chance to survive now that was mean. Kaidan shot the first target. Wen the second moved to see what happened he used his biotics to tap the enemies vitals and easily dispatched of the third. Then he heard the shots from somewhere in the back, that must be Charles. The mercs got uneasy and started moving out of the room, Only to stumble over their fallen comrades. Good thing he took the M-11 Suppressor they never heard where the shots came from.
After he had taken out his fifth merc, there was no movement anymore, he had to get closer to the door now. "Charles status?"
"Counting those that you took out nine down. The Leader is bunkered down with two others, we don't have a clear shot."
"Okay. I'm moving to the door give me cover."
"Acknowledged."
Kaidan made his way to the door in silence. If he could get the jump on those mercs maybe Charles could get a clear shot. But before he could look around the corner all hell broke loose.
Bullets where flying left and right. He heard something heavy crash into the floor. Kaidan tried using the short moments where there where no gunshots to get a view of the situation but a thick smoke screen blocked his view.
When he finally saw one of the enemies, Kaidan tried taking a shot at him. But something threw him back. In the last moments before he lost consciousness he heard the typical mechanical sound of the geth voice. Designated ally...
Everything went dark.
A few floors higher up Garrus and James where drawing the mercs to their position. Jundom Bau and his men had fallen back to the council chambers.
"Now this is FUN" Wrex had roared over the sounds of battle.
James had lured the mercs towards Garrus so he could take them out one by one.
At some point they had heard an explosion somewhere in the distance. "Must be somewhere else." James had yelled through the floor.
Garrus was worried the only other big merc group left was where Kaidan was heading. Hopefully it wasn't near him.
It didn't take long before Wrex stormed out through the hallway, quickly followed by the council. The rest of the mercs suddenly started running a big heavy krogan in a battle rage is frightening after all. Garrus placed his shots carefully and the last mercs that came close got to meet James who waited around a corner for them.
When the last merc lay at their feet Garrus called in to EDI to update their status.
"What do you mean lost contact to Kaidan and Charles?"
"Kaidan is disappeared from my sensors along with everything in the labs wen that explosion went off."
"Damn EDI, any mercs left?"
"Only smaller groups. The path to the labs is showing no activity however. Garrus my sensors indicate no life signs in the Labs."
"Shit. James!" Garrus yelled to the marine. "Grab the council escort them to shuttle alpha. I need to check on the labs something happened."
"Scars you don't mean the major and sparks are..."
"Nah, probably nothing. Just making sure. Lady's, gentlemen, Wrex please follow the nice marine to the shuttle bay. I don't take no for an answer, a spectre told me to get you to safety and this place is sure not safe."
"Sure Garrus, but I sure as hell hope you finally got some better food on that ship." Wrex grinned.
James laughed "Hey we even have a bowling alley in the cargo bay. Plus I believe someone left a barrel of rincol for a certain guy named wrex."
James leaded the council and admiral hacket to the docking bay.
Garrus moved to the labs in fear of what he might find there.