I'm thinking maybe it wasn't that the Creep was more "patient" with the other guy Mitch. Lucas held back because Mitch is not the type to take it well for Lucas to grab the pieces out of his hand and tell him "you can't do that, you can't do that, you can't do that". The Creep is afraid to bully Mitch.
Spot-on.
If Lucas is nicer to someone, especially someone that he doesn't want something from, it's because he's intimidated.
It's actually kind of fascinating; when Jeremiah interviewed Lucas in the final Golden USB show, Jeremiah was affecting a more therapist-type tone, differential and polite, the way Goldaor used to...perhaps taking his cue about how to conversationally approach Lucas from the previous shows. So of course, Lucas immediately felt free to insult the guy, call him a motherfucker, and get extremely belligerent. During the "Mia's Dad" phone call, Jeremiah successfully affected a tone of authority, not just because he was pretending to be Mia's father, but because of the way he deepened, perhaps unconsciously, his voice... and struck a fatherly-concern tone. Although the circumstances were not the same, and we could suggest that perhaps Lucas's early caution during the phone call was due to his fear about being stranded in L.A., or the idea that he put a foot wrong by interacting with an underage girl, I still believe that the polar opposite reactions that Lucas had to these two conversations with Jeremiah suggests a lot about how Lucas's fear of men is the only way to get him to act like a normal person, however temporarily
The comical fashion in which Lucas became all "Yessir / No sir" with Jeremiah during the Mia's Father call tells you quite a bit about the likely way Lucas interacted with his own father.
I absolutely agree that Lucas gradually getting comfortable in essentially browbeating or otherwise pushing people into playing games with him @ Mallon Place could lay the seeds of his eventual ouster.
When Lucas gets comfortable, the REAL Lucas comes out, and the REAL Lucas is selfish to such a pronounced antisocial degree that he's almost certain to commit transgressions which are unsupportable to any living environment.
Then again, the medication seems to have really taken the edge off of his anger, which is good for Lucas keeping a roof over his head, but makes him quite a bit more boring, obviously.
It was sort of a stupid Revelation to me how, absent the rage that makes him froth at the mouth and scream while stalking down the sidewalks of Spokane, Lucas's most salient feature is his moronic repetitiveness, entreating the world over and over again with the phrases he desperately seeks to make true, choruses to shape the reality he lives in into a place where Lucas is a misunderstood genius, a victim of circumstance and bigotry, and not a crazy bum.
Without anger, Lucas is a broken record, and because his anger seems to be so closely tied to his libido, when pharmaceuticals blunt the edge of both, it's just board games & food.
Lucas's use of the internet is kind of fascinating as well. He uses social media, as many people do, to try to brag, but because his life is so meager, his braggadocio comes out in the form of political hot takes, (to emphasize his superior intellect and philosophical morality) occasional sad bait for partners, (currently in the form of the hilarious "My dad has 12 acres, BBQ, and a cow! AREN'T you jealous DON'T you want it?!?!") and the self-soothing control-stimming that he gets from boardgame creation. Lucas's impatience with Jamie being unable to remember or follow the newly created (and likely overly complex) set of rules, tells us that what we all suspected was correct: making games is about Lucas "making the rules". CONTROL.