Octavia having a severe night terror. She is remembering when she messed with her mother car, which resulted in her death. Her old pet Parrot getting torn apart, her mother coming back and the drugs they used to give her in Juvie 

Wanda room was closet to her so she went in. (Via window before Octavia dead locks her door when she sleeps and sings her lullaby to her

https://youtu.be/sVtX2BSYIJg

Her and Wanda goes way back. Far back to when they were humans. She and Wanda always got in mischief together. Sometimes They play and sing. They were forced to stop seeing each other after there respective parents died but when they first arrived in Juvie they ran into each other. They were happy to be reunited