Name: Nightmare sans
Species: Negative guardian aka negative spirit and Skeleton
Age: 19 years old forever
Gender: Female
Sexuality: Pansexual and polygamy & polyamory
Looks:

Ps give credit to the creator and this is what she looks like in the future she has MZ cup breasts

This is what she looks like in the past.
Personality: Loving and caring,Optimistic and kind,overprotective, Autism,PTSD and depression,Omnivert,Shy,Generous, She has a pure soul of gold and she is pure hearted even after she got corrupted, is super smart and intelligent, is very sweet and affectionate,is tsundere, has trust issues, suicidal, Sensitive, Has autism and is autistic, she has a my personality mixed with Nightmares personality
Abilities: Negative Aura, Shapeshifting, Regeneration, Social influencing,Telepathy, immortality, Empathy, corruption, other unknown powerful abilities and has regular Sanses abilities, Negawarp, TORMENT OVERLOAD, Petrification
Hobbies: Reading books,singing, Hanging out with Ink,Error & Killer, listening to music on her unbreakable iPhone 8, Texting ink,error & killer on her iPhone 8 and they have each other's phone numbers
Likes: Her deceased father in her last life,Her soulmates, her little twin brother Dream, Chocolate and skittles and coffee,Reading books in her library
Dislikes: The villagers, Her mother in her past life and bullies from her past life,Fate
Soulmates & Lovers: Error,Ink & Killer
Soul color and traits: her soul trait is Negativity and all the human soul traits and her soul merged with the purple fireball that is nightmare and her soul looks like a monster and human and apple merged together and her soul color is All shades of purple and violet and her soul is also black
How Nightmare met Ink, Error & Killer
Nightmare met ink before the apple incident and they became close friends with each other and they known each other for 99 years and she met killer when she formed her gang aka her family and she became close friends with killer as well and they known each other for a long time and Nightmare met Error after she ate the apple and they became close friends Nightmare Loves all of them deeply like for infinity and they are all soulmates and since they knew each other for a long time they formed a unique and unbreakable bond.
Ps Ink has a soul but it is locked 
iPhone 8 looks: her phone case has lavender flowers on the case and her phone is undestructible  and her background picture is a picture of her and Ink,Error & Killer together
Nightmare is Super super super powerful and she has a lot of powers and abilities she doesn't even know about and she is good at Martial Arts and parkour
Weapon: Negativity knives and Scythe and staff
In my Au they all have hair and Nightmare has periods and her periods are really painful.
Nightmare has a Female ecto and it's Violet and cyan