1. Kris isn't kept hostage by the SOUL, but rather shares a body with it. The Knight just possesses Kris to use the vessel to create Fountains.

2. When you look through the room Queen trapped you in, there’s a calendar with a vacation date circled from a search query about when college has summer break. Given how close Asriel and Kris seem to be, I’m pretty sure Kris is really anxious to see Asriel and have his support back. There’s another curious thing where if you decide to look through Asriel’s room, Kris shuts their eyes and seems to not want to see what’s inside, despite what the Player might want. Why? Afraid of what they’ll see? What could Asriel possibly be searching for that Kris would be afraid of the truth? I think some incident happened in the past, one that’s related to the Dreemurr and the Holiday family growing apart, Noelle’s sister “Dess”, and Asgore apparently being removed from the police force. Circling back to Kris, there’s several details that hint to Kris’ mindset, and basically, I think Kris doesn’t want to grow up because when you grow up you grow apart and don’t live out fun fantasies anymore. If you go to the flyer in the librarby,  and read the one about the ICE-E event that says “Where teens can still be Kids!” Kris is relieved, for some reason. Probably because they’re glad to hear they still technically count as a kid. Not directly related but if you go up to the upper-right room and read the book about humans, Kris quickly shuts it. Given the similarities and hints to Chara from Undertale, it seems like Kris wanted to get away from other humans or humanity in general. Which also aligns maybe with Kris being fearful of the bunker. I really don’t know what to make it past this though. Crack theory was that the world of Undertale was just a Dark World Kris made as a kid or something. Or that when “Chara” fell, it was a fall similar to how Kris and Susie fall when entering a Dark World.

3. The Dark Worlds seem to function as some sort of escapism, and it’s interesting that they’re all based on real life things. In Chapter 1, the Dark World was based on the classrooms various toys like checkers, chess, cards, dolls,etc. In Chapter 2, it seems even more so with Noelle. Queen actually wants the best for Noelle and is very nosy and always chasing after her, in contrast to Noelle’s real mom who is always busy being a mayor. After all, Queen does know how sad Noelle’s search history probably is. Kris probably feels the same way, as both Noelle and Kris grew up together and seem to be suffering from dysfunctional families or some sort of drama. And Queen directly says in the boss fight with Berdly that the internet and the screens provide comfort for many people, and she is well-intentioned in wanting to help make people happy. Maybe for Kris it’s video games or roleplaying or toys or silly things, kind of like how many people in the real world do similar things.

4. So at the end of Chapter 2, Kris rips out the Player Soul and slashes the tires to Toriel’s car. Then later Susie talks about how cool it would be if they could bring Ralsei and Lancer and everyone to their world and hang out with them. Then Kris takes the Player out once again and pulls out a knife, fills the “Blade” with their “Will”, aka Determination, and creates a new dark fountain that encompasses their whole home. It seems that the tires were to ensure Toriel stays inside the house though, so maybe it’s just the house. If that’s the case, and Kris really is the knight, I think Kris wants to envision a better home where things are better. Escapism right inside your own home. If it’s the whole town, then maybe Kris already had Susie’s idea and really is going to take everyone in a new Dark World so everyone can be together. That or Susie inadvertently gave Kris the idea. The other reason I could see it being a town-wide thing is because now Kris has the knowledge of the Roaring (thanks to Ralsei). If you do the snowgrave route, Noelle doesn’t even recognize it as Kris’ voice. The sinister voice in that route seems to be the Player rather, being cruel and making Noelle make these traumatizing choices.

5. The blatant "parralel universe" shit. 'Kris' is an anagram of 'Frisk' (without an F) and also 'Ralsei' is an anagram of 'Asriel'. In the end of Chapter 1, Ralsei shows he is a Goat Monster, like Asriel, and he is a prince of Dark, meanwhile Asriel is a Prince too (He could be the Prince of the Light). The monsters, like Catty and Bratty hates each other, while Undyne and Alphys don't know each other. They're not in the underground too.

6. Lancer and his dad have a spade symbol, located in both their stomach and their face. This could mean that there are 2 more Kings/Kingdoms of Darkness because Ralsei is Heart (and Asriel using the Heart locket)... he have a Heart Symbol in his Chest. That also means that there are actually 4 Kingdoms of Light, with the 3 Kings that was captured by the "weird knight" and Asgore/Asriel was the last Kingdom not captured by the "weird knight". Not only that, Jevil is like a Black Joker, he shoots both spades and clubs which is both black, and Jevil has a J in his name, because he is both a Joker and a Jester.

7. Well, if you’ve played through a Genocide run in Undertale or watched a playthrough of one, you’ll learn of the existence of Chara. They’re an evil human entity who slowly gains the power to take over Frisk’s soul at the end of the game. Once you complete a Genocide run in Undertale, Chara becomes bound to Frisk, and they destroy the world you’re currently in before going in search of other worlds to ruin. And after completing a Genocide run, you can choose to play through the game again as a Pacifist. However, in order to see the Pacifist ending, Frisk had to give up their soul to Chara, which results in the Soulless Pacifist ending, and Chara attaining unbelievable power. Keeping all of that in consideration, it’s entirely possible that this Deltarune universe might be a new realm that Chara is looking to invade. After all, the Deltarune application itself is called a survey, which has two meanings. The more common meaning is that it’s an application used to collect data for research purposes. But “survey” could also refer to scouting or surveying unexplored territory, and maybe that’s what we’re doing here. Chara is in search of a new world to destroy.

But hey, those are just theories!

GAME THEORIES!