I see lots of cool headcanons where Dr. Picani has Thomas as a client and ends up meeting the (Sanders) Sides, or joining them in Thomas' head in one way or another.
But what if the reverse happened? What if the sides became characters in Dr. Picani's inner world?
I mean, I love cartoons too. So much so that the characters I love most often become integrated into my inner dialogue, the way my parents or teachers or friends did when I was little. Fictional characters are like imaginary friends to me, just like Thomas' Sides are to him.
So consider:
Picani has an incredibly flexible and vivid imagination (shown by how easily he can map his clients' situations to cartoon characters).
Picani is also incredibly empathetic, and empathetic people tend to "absorb" the emotions and mental states of others easily.
Thomas would likely describe (or maybe even reveal) the Sides to Picani as characters, since this is how he understands his own thoughts and feelings.
Picani loves stories of cartoon characters going on adventures and solving problems, and finds them deeply symbolic; he also likes psychology enough to earn a doctorate in it.
Therefore, you better believe Dr. Emile Picani is going to be the world's biggest fanboy over imaginary characters that help Thomas to solve problems by symbolizing aspects of his psychology.
What if Picani spends a session, say, helping Thomas make peace with his tendency to lie to himself. And when he goes home at the end of the day, he's still geeking out over how clever and creative his client is - he made his thoughts into a literal dialogue with a storyline and everything, like, how freakin' cool is that?!
And then he opens his closet door to find a tall, sharply-dressed man in a bowler hat standing over his dusty old running shoes.
"It's good you're keeping these, darling," the man drawls, voice smooth as silk. "New Year's is just around the corner. I'm sure they're going to see lots of use."
