So, i was thinking, what if we had an Underswap Take with modern UT and DR knowledge? Welp, here is my idea.

The swaps keeps the same, except for:
Frisk - Kris
Chara - Asriel
MK - Susie
Flowey - Rosy (new char, that flower on Kris' arm)
Mettaton - Mad Mew Mew
Napstablook - Shyren.

Rosy would keep following you 'till the end, and, since Toriel have not conquered any souls, there won't be an Photoshop Rosy fight, tho, a Chara fight would definitivally happen.

Lorewise: So, after the monsters lost, the humans scouted them to an island, and locked the up on a Dark World. When the first human came, they tried to erase that dark world, but the human died by rose-poisoning. Asriel absorved their soul, freed the monsters, but, it was futile, because the humans killed the prince, and locked them in a dark world again, making freedom seem hopeless. Time passes, and Kris gets curious on the island, opening a door that traps them in the Darkworld. The fountain is guarded by Toriel, who is still in grief by the loss of her children.

That's the idea, the swapped chars would keep their original personalities, that means Kris hates you, and will rop you out of them the moment they can, lol.

Funfacts:

- Originally, Rosy would be Ralsei.

- Toby Fox grew up with Earthbound, and used Starman's symbol on Papyrus. I grew up with Sonic, so i added Shadow's symbol on Sans, lol.

- The color schemes of the royal guard got swapped with MTT Box's color scheme.

- Sans is a royal guard, but he ain't the best at his service.

- Papyrus doesn't smoke.

- Other than Sans and Papyrus, everyone that has a Dark World color scheme will use it.

- Susie joins your party.

- The color modes switch aswell, being:

Yellow Soul - Switch Soul (the Mad Mew Mew fight soul)
Purple Soul - Orange Soul (would work similar to the one featured in Bad Time Trio).

- They were stuck in a cave on the island, so there aren't any darkners in this AU.

- Rosy was based on the SMW Fire Flower.

- Sans' cool dude outfit is just the cassino fit from the Xbox version, without the jacket.

- Sans can now open his mouth, but Papyrus can't.

- Papyrus have the glowing eye. It's the same as classic UT Sans.

- Alphys isn't missing an eye, but Undyne had a robotic one.

- The Mad Dummy is swapped with the Mettaton Box form.

- Snowdin is swapped with Hotland.

- Asgore and Asriel keep some of their prototype design's fetures (black hair, emo hair).