(I also had some Thoughts regarding Mabel and Bill’s DR verses
First of all, despite her knowing full-well that it’s a game, Mabel will still do everything she could to protect the folks within it. Being stuck in a video game while waiting for Dipper and the others to come pull her out is not the weirdest thing to happen to her, so she’s gonna focus more on making friends and keeping everyone (especially Bill) from committing murder.
Of course, this is all while trying to pretend they AREN’T just trapped in a video game, because why would she wanna shatter everyone’s reality like that? Nah, nah, she’s gonna be the best darn friend to these people as she can be and hope that it’s enough to make all of them not want to kill each other.
And since she’s now the Ultimate Artist, that absolutely comes with at least 200% more glitter bombs, since she somehow has an endless supply in her pockets now. Thanks, weird murder game, for at least giving her one of the BEST Ultimate Talents ever!
Bill, on the other hand, is perfectly happy to just drop a ‘Haha none of this is real, or at least even less real than the reality outside this place, and you’re all just characters in a video game.’ whenever he can, and to threaten murder in the most creative ways possible.
But since he’s been branded the Ultimate Liar, it’s probably pretty hard to take him seriously. It also probably doesn’t help that he’s still stuck as a powerless little thirteen-year-old. Maybe if he was back in his original triangle body, everyone would be more afraid of him.
But alas, you do what you can with what you have. And he has his words and a fleshy teenage body, both of which can be used to be the biggest annoyance around.
Now, would he actually go around killing anyone? Probably not, he’d likely have a lot more fun with just causing chaos and making people (Mabel) THINK he’s going to kill someone rather than actually doing it.
Although he may have considered an attempt on her life a few times, but since she’s obviously aware of the kind of things he can do, she’s always too on guard for him to actually go through with any of those attempts. Plus she can beat him up, and they both know it.)