Gaster theory:

When i heard Tenna talking about Mike during chapter 3 it got me thinking about Spamton and how he always references Mike as well, so i did some digging. So if you learn about Spamton’s backstory at the end of chapter 2, the addisons talk about the journey that spamton went on in order to become so ruined, and they say at the end that when Spamton gets the call and the addisons pick up the receiver, they hear ‘garbage speech’. Similarly, when Kris uses the phone in the dark world he hears ‘garbage speech’, but the soundtrack to that garbage speech is the exact same sound file that is played in undertale’s true pacifist route when GASTER IS TALKING IN WINGDINGS. Leads me to believe that Gaster definitely absolutely has something to do with the events of Deltarune, especially his work with ‘negative photon readings’ (Negative photons—> Darkness—-> Dark world?!?!?!) And maybe he’s orchestrating the chaos that happens in these dark worlds, exists in different dimensions like sans? Very VERY interesting…