Eren cut himself by mistake and he turned into Titan. Eren Is too weak so he have only half of Titan body so Eren Is still not inside. Everyone did cyrcle around him and wanted kill him because they thought that Eren betrayed them.

Eren: Hey hey hey hey hey!! Calm down!! It's mistake!!

Suddenly you came from Eren's behind and everyone are watching you.

Captain Levi: calmly like always Who Is it?

Eren jumped on the ground.

Eren: smile. That's my friend. She's vampire and fighter.