There is a hidden detail in this scene. The faces in the pain chart here resemble something called the “5-point scale of emotions.”
So, with neurotypical kids, this tool is used to help the process and recognize emotions. But an autistic kid's scope of emotions and reactions can be labeled wrong if you hold them to neurotypical ways to emote and cognitive processing. Many autistic people even learn to mask 'normal' expressions throughout life in order to try to communicate better with neurotypical people. Because being perceived wrong can lead to many isolating and traumatic experiences.
Mel is very expressive, but sometimes you can see her forcing expressions in order to pretend to be okay or fit into the mood around her, and the more tired she is, the more difficult it becomes for her to mask this way. In season 2, she is stressed about the deposition, and she is emoting much less, which makes me think that expressing emotions and then being vigilant about how she is perceived can be very tiring for her. I imagine she got called 'too emotional, too loud" as a kid, and she carries that with her. So the longer the day goes on, she starts staring into space, loses her temper, and shows irritation. She cannot mask anymore and she feels guilty and disoriented her usual coping mechanism are failing.
So her staring at the pain scale chart with the faces on it makes me think she is trying to figure out how to process her own emotions, or more likely, how the fuck to communicate it to others. "rate your pain' and she is trying to figure out the things that have been accumulating inside of her, her own pain: the lack of social life, likely a lack of time to rest and unmask, being sidelined at work, the whole trauma of the job itself. And not only does she have to figure out all of that, but she also has to figure out how to express it in a way so her neurotypical colleagues could understand if she ever wanted to share it. Because she thinks no one is gonna go the extra mile to see it from her perspective or help her try to figure it out. This woman did a whole research project because she thought he had an eating disorder. I think she believes she has to figure out everything by herself. Enter Frank, who actually asks her what she thinks and why, providing a lot of patience while she figures stuff out.
