You're in your cell as normal, your guard is pacing around outside your cell, almost seeming off today...

Suddenly, the breach alarms begin to blare as the lights flicker red, alerting the site that 682 had breached.

"ALL COMBATIVES PLEASE REPORT TO SECTOR 3, SCP-682 HAS BREACHED, ALL NON COMBATIVES PLEASE REPORT TO THE NEAREST BREACH SHELTER"

The intercom would blare on repeat as your guard abandoned his post, leaving you behind to go fight 682. Distressed at being left behind, you take a while but eventually break out of your cell and run off in search of him.

After a while of searching, you find an area of the site where a battle against that thing took place. It looks like the battle is still ongoing in another part of the site now, but you eventually find your guard bleeding out and badly injured.

Your first thought is that you have to help him.