One interesting plot could be that the main character from DDLC, say, the protagonist, gets transported into the Undertale universe. They could start in the Ruins and interact with Toriel. Since the DDLC character is used to a different kind of world, their reactions to the monsters and the unique magic in Undertale would be fun to explore. Maybe they could try to use their knowledge from DDLC to solve some of the problems in Undertale, like trying to understand the nature of EXP and LOVE in the context of their own experiences.
A possible plot is that the DDLC girls somehow end up in the Underground. Monika, being the self - aware one, might try to take control of the situation in a similar way she did in DDLC. But in the Undertale world, she has to deal with Sans, who can sense something is off about her. Meanwhile, the other DDLC girls are trying to find a way home while also befriending the friendly monsters like Papyrus. This could lead to a lot of comical and interesting interactions as the two very different universes collide.
The plot could involve a glitch that merges the two worlds. Undertale characters start to show up in the DDLC world and vice versa. Frisk could end up in the DDLC clubroom and be really confused. The DDLC characters could be scared or intrigued by Frisk's determination and ability to reset. And in the Undertale world, the DDLC girls' presence could disrupt the normal flow of things. For example, Monika's attempts to manipulate the situation could accidentally set off some of the more dangerous monsters in Undertale, leading to a whole new adventure to fix things.
Chapter 10, "Running and Hiding", is the clearest early answer because it turns Damien's situation into a concrete plot event. The chapter turns that into something concrete by moving from Damien was still admiring the beautiful bluepanel that displayed his... to [It stayed this long by utilising its own essence reserve..
Chapter 222, "The Fog Realm", is the clearest early answer because Leana finally turns buildup into a real advancement. The chapter turns that into something concrete by moving from Move, we need to cover a lot of ground today." The blistering heat of... to The impact sent waves of force rippling outward, knocking the....
Chapter 476, "Racing to Claim Land", is the clearest early answer because it turns Dragonhawk Star Domain's situation into a concrete plot event. It opens with After the brief conversation between Gu Hang and Erso had ended, the... and closes on These Green Skins, scattered across various worlds throughout the....
Chapter 462, ", Only the Loser is the War Criminal, The Weak Resort to Treason", is the clearest early answer because the buildup finally cashes out in a real clash. Early on, Kazimir Erso's so-called "encouragement" was not just a matter of.... By the end, Often, such a region may have only one or two connections with....
Chapter 56, "Killing Spree", is the clearest early answer because the violence around Damien becomes final instead of hypothetical. The chapter turns that into something concrete by moving from Damien stood his ground after beheading the demon, awaiting the... to Huh?" Damien was surprised to see the blood eat through the ground....
Chapter 137, "A Little Thief", is the clearest early answer because it turns Damien's situation into a concrete plot event. Early on, Over the bustling streets, the rising sun shone down but there was.... By the end, It'll be a warning to the others." When one man suggested burning the....
Chapter 486, ", Only You, My Friend", is the clearest early answer because it turns Military Affairs Department's situation into a concrete plot event. The chapter gives readers a real answer by opening on Overall, Gu Hang believed that the advantages of this matter far... and ending on The senior figures from the various departments and forces of the....
Chapter 489, ", Fatal Assassination", is the clearest early answer because it turns Spiritual Energy's situation into a concrete plot event. The chapter gives readers a real answer by opening on The limousine exploded violently, the vehicle instantly torn apart,... and ending on Upon re-emerging, Gu Hang felt a surge of high temperature..
Chapter 486, ", Only You, My Friend", is the clearest early answer because it turns Gu Hang's situation into a concrete plot event. The chapter turns that into something concrete by moving from Riding inside, deep beneath the Imperial Palace, the track twisted... to I know we all have our connections, but who would complain about.... What makes it stick is that the chapter closes with I will definitely add an update tomorrow!
Chapter 6, "Punishment For Disobedience", is the clearest early answer because it turns Damon's situation into a concrete plot event. The chapter turns that into something concrete by moving from Within the confines of a large room three times the size of Damien's,... to I'm sure you know what that means." His father said.. What makes it stick is that the chapter closes with Osbourne opened his mouth to ask the question on his mind but Ashbourne was one step ahead.