Arc ?: Gaster
Arc ?: THE 1ST CHILD
Arc ?: HATRED
Arc ?: PHM AMO
Arc ?: AU Obsession
Arc ?: Awful Past
Arc ?: Timelines
Arc ?: Marriage/Soul bonding/Courtship
Arc ?: Alternate Universe
Arc ?: Family/Pregnancy (?)

Depending on the Type of Soul, It will lead to some interesting ideas.

Chara is only able to infect DETERMINATION souls. (So two guys to choose from)
◾Make evil? Maybe cause chaos or build enough Determination to force reset?
◾Maybe just wants to live again. The truth get out?

HATE can infect any souls, except for Kindness.
◾Girl might lose trait, and gain another trait.

◾Chara shows up - Takes over one of the DT humans - Could cause enough mayhem to drain souls of trait, make all gray souls, or even raise LV.

◾A new person from an old AU comes along, finds soulmate, is slowly being killed from being out of the void/AU, character may lose soulmate

◾Lost traits completely, weakened to the point of 1 HP, HATE takes control, starts causing mayhem

◾Near death experience, could make SMs overprotective, causes drama with MC

◾Mob of angry humans, kills one of the monsters, causes character to reset, finds out they hold the reset button

◾Minor Character Death? Edgier Monsters kill humans/monsters? Humans kill monsters?

◾Character gets trapped in the void, meets ???, accepts fate, escapes with new friend

◾Characters learn magic, some start to become infected with HATE/Chara, could end up hurting/killing companions

◾Accidental SOUL absorbing: How do they react? How does it effect character? What happened?

◾Soulbonding time~ Who gets to first? How? When?

◾Dates and cutsy romantic shit! Maybe shopping together, going to a parade, dinner dates, Walking together, training together, etc

◾MC gets in fight, doesn't want to hurt the attacker, gets hurt bad, consequences?

◾Sexual Activities! Who goes first? What style? Romantic or passionate? Should it even be in story?

◾Character gets sent to AU! Has to go through storyline? Maybe Dead AU? Meets up with more godly/out-of-timeline characters?

◾Jealousy! Envy! How do characters react when SM gets flirted with/flirts with others? Do they get violent? Do they get pouty? Do they become attention hogs?

◾Soulmate death? Maybe before the reset ability has been learnt? Character feel regret/betrayal/hatred/anger?

◾Kinks! Who has what? Should be explored in detail? Hidden or open about them?

◾Heat Cycles! Who turns into alphas? Who turns into predators? Who hunts? Who hides? Who stalks? Who comforts? Should it be dangerous? Could they die without a mate during heat? How long should heats last?

◾Should the characters have human Soulmates as well? Would they know? Would it hurt?

◾Dealing with fighting within the family/soulmates/friends

◾How would characters deal with SM's who want to spoil them? The humble ones? The shy ones? The guilty feeling ones?

◾Holidays and Birthdays! How do they celebrate? Do they go all out?

◾Kidnapping! Not enough attention? Alone time? Burgeoning chip? How will the other SM's react to it? Hunt down? Aggression? Acceptance?

◾ Works at MoonTec? Stretch, Sans, Edge (Fired), Papyrus (Quits)

◾ Soulmate is found, had died in other AU. Murder? Caused by friends/brother/guard? How to react??

◾ How to have Children between Monsters and Humans? #HowToMakeBabehs
◾An Agreement between the couple, and magic into existence?
◾Needs to be soul bonded, and needs to have soul sex while having physical sex?
◾The strong intent/desire (Not spur of the moment desire) must be there as the sex is happening
◾Adoption?!?
◾Surrogates?!?

◾ Would she even want to keep the child if she got accidentally pregnant?
◾Put them up for adoption? -Toriel/Asgore, Alphys/Undyne, Parents
◾Terminate the pregnancy? -Body can't handle it, her choice, unable to care for
◾Keep pregnancy for Soulmates? -refuse to care for, soulmates raise, no connection?
◾If Kept, and She didn't want it, how would she act? -Calls herself it's aunt, interact but no motherly desire, complete disconnect?

◾Losing Home?
◾Would she move into soulmates' house?
◾Would she bounce around homes until deciding?
◾Would she be kicked out? Decide to move out? Choose to go her own path?