So we all have theories about what is inside the bubble, but how the actual episode plays out is more up in the air.

Spoilers under cut!

First to Recap:

Weirdmageddon part 1 ends with Dipper, Wendy, and Soos entering the bubble Mabel is in and Gideon risking his life to defy Bill creating the diversion that allows Dipper and company to get to the bubble.

It’s a prison “designed by Bill” as Dipper says and I’ve seen many a theory about how this bubble while being a prison also has the overkill of also being locked up by multiple chains means Bill most definitely does not want Mabel to escape. This is true even in the context of Dipper getting killed off by 8-Ball and Teeth and Ford turned to gold. Stanley is unaccounted for (maybe hiding) and everyone else is too scared to stand up to Bill.

My Theory on the reason Bill has Mabel locked up:

I don’t think Bill even has the power to kill Mabel OR for whatever reason he’s afraid to even try. Mabel is that dangerous for Bill and if she was affected by any of the weirdness waves that transformed people into crazy freaks I’m guessing that could be exceptionally bad for Bill.

Based on Abuelita becoming a recliner armchair, I suspect the weird waves transformations have something to do with a person’s personality. Abuelita is the definition of a truly laid back person in her reaction to the apocalypse. She does not panic, she does not really react to the transformation, she just is in the moment being chill and trusting Soos can fix everything and proceeds to nap after he leaves. So “Nothing is greater than the power of” Mabel “I AM A GOD OF DESTRUCTION!” Pines–the little girl who believes she can fix PRACTICALLY ANYTHING with glitter, stickers, hugs and sweaters–the girl who will find a round-a-bout way to fix a problem nobody thought of before, could literally become something threatening to Bill.

However the weird waves didn’t seem to affect some of the characters so I could be wrong, it could be completely random who gets changed and what they change into when exposed to the waves (I will place money on the mailman becoming a wolf-man).

So how will the episode start off? Well imagine if you were in a bubble prison, or rather you woke up in a prison how would you react? More importantly when you are in a prison designed to keep you from leaving rather than punish you for undesirable behavior (like prisons for criminals such as Gideon) what would it look like? The best way to keep someone from moving is to make them comfortable, make them feel safe and secure and make them happy. Mabel was in there for three whole days and the design seems to have needed reinforcing as the bubble grew larger in size. The size expansion could be explained as many others have theorized by one simple explanation.

Mabel Pines is trapped in her own Mindscape:

Mabel Pines is a girl of infinite imagination and creativity, if left in her own mindscape to her own devices she could conjure millions- no BILLIONS of things and stories in a dreamscape if she was aware she was dreaming at all. Even dreaming regularly would create countless scenarios, some based on memories replaying and playing out “what could have happened?” events, and predictive future events based on current information and general imagination shenanigans of the surreal nature.

I wouldn’t be surprised if the Legend of the Gnome Gemulet plot line was only canon in a “what if” scenario Mabel’s mind generated as a “what if Stan never tried to reactivate the portal to get Ford and the government guys never tried to arrest him?” series of events since it wouldn’t fit in the canon timeline being post NMM. The reason being that NMM was the night Stan’s countdown began and the next morning was the “crazy rooftop fireworks party” from NWHS. After all, the timing of the game’s release was between the episode where we see Mabel fall asleep and the one where we see her trapped in a bubble (though it could be a coincidence).

Another idea relating to this is that Bill’s chains may act as a not just physical barrier to the world outside Mabel’s prison but also transmit information Bill has about the town’s citizens to make Mabel’s dreams feel real, to counter Mabel’s lack of knowledge of other citizens in Gravity Falls and make sure she doesn’t realize she’s trapped (because she would be put off if everything was too perfect or predictable).

If we assumed she spent three days time or longer in dream time there could be moments where Mabel realizes things don’t add up. At first she thinks she’s mis-remembering things but as these details add up more and more she remembers the disappointment of the reality of high school, then that Candy and Grenda said they couldn’t come to her thirteenth birthday party, and finally the fight with Dipper. She would ask them about it and they would respond after a delay, and claim not to know what she’s talking about, because Bill’s chains are also acting as a block preventing Mabel from remembering the rift breaking. She only remembers running off and everyone tells her she must be remembering some bad dream she had a few days earlier. Then the real Dipper, Wendy and Soos show up after wandering her vast mindscape searching for her. Dipper apologizes for the fight and the rift and then it all comes back to her. The dream starts to become a nightmare in response to Mabel’s sudden change in emotions and acceptance of the reality of her situation.

So basically, as the Mabel POV story goes on we could get the Dipper, Wendy and Soos POV, OR the Stanley Pines and other citizens of Gravity Falls POV as the B-plot. If the latter B-plot is what we get; all of it would likely be parallel to the events of Weirdmageddon part 1 (all events take place in the span of either the three days before Dipper heads out to save Mabel or during the day of Dipper heading out to save Mabel), with the episode ending when Mabel encounters the real Dipper, Wendy and Soos leaving a cliffhanger on how they’ll escape.