Yeah

First idea: Underelements

- is one of those AUs where the characters control elements but different
- the monsters are split into two categories: Guardians and Elementals
- Guardians can have up to three elements and normally guard something relating to an element. For example, one Guardian might guard a tree
- What they guard also influences their power
- Elementals are a more powerful form of Guardian and do not need to guard anything
- They are fewer
- The Guardians/Elementals were locked under the mountain because they wouldn't let the humans destroy habitats for more houses n shit
- The most powerful Elemental who was killed trying to defend everyone used her last amount of power putting a curse on the humans. Every thirty years a human would be born with the power of a Guardian
- That's why the humans fall down the mountain in this story
- Toriel and Asgore are both Guardians, Torieo being fire and Asgore being nature
- Asriel was special because he was born from two Elementals. He had the powers of nature, dark and light
- Sans and Papyrus are water and ice Guardians respectively
- One of Undyne's parents was an Elemental so she was born with two elements, water and light
- Alphys is a lightning elemental
- The ghosts are special guardians, being able to control plasma
- All the monsters in the ruins are fire Guardians, an exception being Whimsun who is light
- The children were all different elements, except for Chara and Frisk who were both magma
- Patience is ice, Integrity is water, Kindness is nature, Justice is electricity, Bravery is earth, Perseverance is darkness

Second idea
An au where most people are amalgamates

- When I say most people I mean it
- Papyrus, Chara, Asriel, Undyne, Monster Kid? All amalgates
- Gaster is too
- Alphys, Nice Cream Guy, Burgerpants and Sans are scientists
- Nice Cream Guy and Burgerpants are really bad at their jobs but Chara and Asriel like them because they bring food all the time
- Frisk is an experiment, floating in a tube somewhere. Their eyes are yellow and they do not show emotion when talked to
- Chara and Asriel became amalgates when Asriel tried to seperate their souls in An attempt to save their lives after they got attacked
- Everyone else is an amalgate because of an explosion in the Core while a determination experiment was taking place. They were trying to see if determination would help bring more power to it
- None of the amalgates can fully talk. Undyne can groan out words with one syllable, but even then it's hard for her to be understood
- They all gain a few animal-like characteristics
- Chara tends to hang out in the darker corners of the lab, only coming out if there is food or if there is something they want to check out. There's an exception if Asriel is in sight and wants Chara to come out
- Undyne likes to be near Alphys but is otherwise on her own and quite hostile to other amalgates. Because of this, she has to be moved to a completely different room if the other amalgates are getting fed
- Asriel has the reputation for being a kinder amalgate. He doesn't fight any others and in return they don't fight him. His form is very unstable compared to others though, and has the tendency to melt when overstimulated. He also melts on Chara, sometimes, when he's tired
- Papyrus is literally like a dog

Welp those are my only ideas atm. I know I have more but I can't put them into words so