how they are out of the session, like if you see them interacting with co workers or their family...

if you see them react under pressure to an unexpected situation etc

i would say a lot of their personality could be a real part of who they are, that we see ins session but a lot of it is also how they are "with every client" to a degree so it's the therapist act so to speak. that's why i watch for how they are with others or in other situations they don't control