She wandered uninterrupted for a while till she found the cafeteria and it looked like it was food time. Shadow jumped down the steps and made her way to where she saw the food, good it was something she could eat. 

She grabbed some fries before walking to a corner of the room. She sat on the floor and began eating. She went unnoticed for a long time till she felt something burning her forehead a bit. Shadow looked up only to see down the barrel of a gun.

"How did you get in here this area is off-limits to civilians."

Shadow was confused till she remembered she changed, she was clean so they didn't recognize her.

"Sir I can assure you I'm meant to be here."

He had his helmet off you she could see his expressions, and he was not amused.

"Then I will need your identification girl."

Shadow just smiled and opened one of the pouches on her belt, pulling out her ID, and handing it to the man. He took one look and his face changed instantly to shock and a little fear.

"Oh, right you're the new girl with the immunity, sorry about that."

Shadow just smiled and gave an ok before going back to her fries. After that everything went by smoothly and the guard began to protect her and tell the others she was fine. When she finished she threw her trash away and thanked the man before continuing on her adventure. 

After some searching Shadow found the holding cell for 682 and was able to pay him a visit as she promised. Eventually, she was found and forced to leave but this time 682 was more ok since he knew she would be back.

After that Shadow walked for who knows how long before she happened upon something that caught her eye. It was a completely clear door and that was something she had never seen, this must be investigated further. 

Inside the room was sitting a boy around her age, she was 15 now, and he was sitting against the wall. After only a few minutes she was found and told she was needed, but Shadow had a feeling she would be seeing this boy, who said his name was Clark, again soon.

So now Shadow spends her days wandering the facility and talking with the SCP's. Helping with experiments and getting into trouble. This was how inmate D-9560 became Shadow, SCP-SVR, and subsequently the most powerful and deadly SCP there is. But those are stories for another time, as of right now all you have to worry about is where on earth Shadow disappeared to and which SCP is she with right now.