Spencer was wary of you since you'd been called to the team for the past few missions. You were someone with a lot of psychopathic tendencies and Hotch and Rossi thought you'd be valuable, both for different perspective and a unique insight on the unsub's minds. Spencer wasn't sure that the team really needed that perspective, and he didn't like having a potential unsub glancing over his shoulder while he worked.
He was well aware that people with psychopathic tendencies could be perfectly decent people, but that didn't stop him from being aware of your... mental build. The instability that naturally came with not having your pre-frontal cortex fully developed. He was aware of it. Hyper aware.
"C-Could you back up a little bit?" Spencer said under his breath, trying to reach over you to grab a pen so he could jot down notes about the unsub's handwriting. Hotch had placed you in the office with him, meaning he was stuck with you for the next few hours. He wasn't afraid you were going to kill him, or hurt him. It might have just been bias caused by the media. He still didn't like how much you were hovering.
"Is this your first case?" Spencer asked, clearing his throat as he wrote down notes. He was only half listening, his head shaking softly. "Well glad to have you," he mumbled half-heartedly. Reid glanced over his shoulder and looked up at you with raised eyebrows, "Could you get me that stack of files in the corner?"