Per 
It was another horrible day at Site-64 in Northern Canada, Dr. Mark was holding his report folder about his transfer to Site-29 located in Greenland. Until one of the Administrative Personnel bumps into Dr. Mark intentionally, spilling his coffee and messing up the transfer documents.
"Watch where your going. Muppet." The Administrative Personal said before walking away without apologising.
Dr. Mark looks at his now messed up transfer papers before thinking. "Those assholes, this is the second time my only chance to transfer from this site gets ruined."
Until when he was at the cafeteria, he was simply grabbing a plate of Mutton Casserole, until a Research personal took the last plate.
"Go away Mark, this is for me." The Researcher said to Dr. Mark harshly.
That has made Dr. Mark immediately get really pissed. When he first was enrolled to Site-64, he was once a happy researcher without any anger outburst, but now is the day that Site-64 sees the wrath of him.
Dr. Mark immediately grabbed an empty food tray and smacked it at the researcher, causing the researcher get thrown off his feet and on the floor with him coughing out blood. Which Dr. Mark left for his office to make a phone call.
At his office, he gets multiple inboxes from Foundation critics hating him to Site Directorates making a fool out of him. Dr. Mark then immediately grab a small business note and grab the phone receiver before punching in the number from the business note which bears the Chaos Insurgency Delta Command insignia.
As the connection successfully connects to the Chaos Insurgency, Dr. Mark then recited into the receiver:
"This is Dr. Mark at SCP Foundation Site-64. I am a defector willing to join the insurgency and throw off the foundation, however by Foundation guidelines I am unable to deflect on my own. I herby declare myself as suitable for being recruited by the Insurgency and request my immediate retrieval from Foundation Custody."
Until he was stopped by members of the Intelligence Agency which then brought him to the Interrogation Room, he was cuffed and held for interrogation by Site Director Lankstrom.
As Lankstrom continuously threaten for Dr. Mark to admit it, Dr. Mark didn't fall into Lankstrom's interrogation tactics, until Lankstrom decide to terminate Dr. Mark on the spot.
However, a gunshot rang out, as Site Director Lankstrom was shot in the chest by a Chaos Insurgent. Lankstrom stares at the smirking Dr. Mark before Lankstrom fell to the ground now dead.
"On your feet comrade, ready to make your employers see your dark side?" An Insurgent said as he released the handcuffs from Dr Mark and pass him a 6-shooter revolver.
Dr Mark then says:
"Oh please Major Dimitri, they broke me too much. Let's make this site pay for the damages."
Gunfire is heard outside the interrogation room followed by a Raid and Riot Alarm blaring, which Major Dimitri and Dr. Mark explode the interrogation room door open as Chaos Insurgents has raided Site-64, killing security personnel and not sparing scientist whom Dr. Mark knows as enemies.
A researcher ran past Dimitri but he shot them in the leg, which Dr. Mark approaches the researcher and looked at them, which he sees is the same researcher who mocked him at the cafeteria. The researcher looked at Dr. Mark fearfully as he never saw Dr. Mark this angry and rageful before, the researcher repeatedly begged for Dr. Mark to spare him, until Dr. Mark bitterly shot the researcher in the head, silencing them.
Until Dimitri and Dr. Mark continue down the hallway, as they witness almost every personnel of Site-63, once bullies of the Foundation. Being gunned down by the Chaos Insurgency when they even begged for them to have mercy, they were effectively silenced when one shot rang out.
A Site Director then tries a futile attempt to kill the duo, until Dr. Mark shot the Director in the leg before finishing it with a headshot. Dr. Mark approaches the Director's dead body and crushes the skull of the dead Director before following Dimitri out of the facility.
As they exit the facility, they see the chaos that was induced. Multiple Insurgents fired rockets to incoming Foundation Apache's, which a rocket hit an Apache and it crashes into the Main Street of Site-64 which killed the pilots and Mobile Task Forces inside the burning wreck.
Until Dimitri and Dr. Mark approached to a Chaos Insurgent APC before they board it and drove to a Chaos Insurgency Base Camp where he will be recruited as a Chaos Insurgent riflemen to take revenge to the foundation.
Site-64 is now defuncted as the Chaos Insurgency has disable the site from the Foundation's Grid and made it into a Chaos Insurgency Base of Operations.