Sonia Marston-Babiole is an original half-human half-cat monster character from the Toby Fox game Undertale.


Eye Color: yellow (right), red (left), black cat pupils

Clothes: pun shirts, black ripped shorts, red and black sneakers, yellow heart necklace, black hoodie, dark blue rose on a light blue bow hair clip

SOUL Color: Yellow with cat whiskers

Hair: black

Skin: peach, black cat ears

Other: instead of human teeth she has cat fangs and claws instead of nails

Font: Babiole (I know WD Gaster, Sans, and Papyrus are the only ones that speak in fonts, but I thought the concept was cool, so, therefore, that’s Sonia’s default font)


Leto Babiole, Sonia’s birth mother, was, by virtue of a glamour that made her pass as a human, able to avoid being sent to the Underground with the other monsters. Forty-four years before Frisk fell into the Underground, Leto met, and later fell in love with and married, Cole Marston. Six years into their marriage, Leto gave birth to what would become her & Cole’s oldest daughter Caitlin. Leto felt half-relieved, half-not that Caitlin was fully human.

The next seven years were the happiest Leto and Cole had ever been, with baby number two on the way. However, that happiness didn’t last forever. The moment Sonia was born, Leto saw two tiny black cat ears on top of Sonia’s head. The moment baby Sonia opened her eyes, Leto saw one yellow eye and one red eye, both with cat eyes, staring back at her. Panicking, Leto quickly covered baby Sonia’s head with the blanket and applied a glamour before letting Cole in to see her.

Unbeknownst to Leto one year after Sonia was born, a human child had fallen into the Underground.

Four years later, Leto and Cole took eleven year old Caitlin and four year old Sonia out to play in a field of golden flowers. Other families were there, as well. Leto didn’t tell Sonia the truth about what she was yet. She couldn’t bare to as she watched Caitlin make a flower crown for her happy baby sister.

Little did Leto realize that she wouldn’t have to.

For a monster appeared.

That monster was Asriel, who was holding the dead body of a thirteen year old child.

The shock of seeing the goat monster holding a dead child shattered both Leto’s and Sonia’s glamours.

Everyone was screaming, women running with their children back to their homes. Men, on the other hand, fought Asriel in an attempt to avenge the child. Asriel, however, held back, resulting in his death.

The age old fear of monsters reared its’ head once people, Cole and Caitlin included, saw that two monsters lived among them.

Leto and four year old Sonia.

The whole village demanded punishment for the death of the child, and that punishment was given to Leto and Sonia without much resistance from Cole or Caitlin.

Sonia cried out to both her daddy and big sister, tears streaming down her face as they dragged both her and Leto to the summit of Mount Ebott. Yet they were silent.

Leto held Sonia tightly, sending pleading looks to her husband. Cole, however, looked at her with such hate and distrust.

The crowd first threw Asriel’s body down into the Underground, followed by Leto, cheering loudly, ignoring Sonia’s screams of “MOMMY!”

Sonia was next.

The last time she saw Cole & Caitlin Marston, Cole’s grey eyes were cold as ice, and so were Caitlin’s green eyes. ( ‘you’re not my daughter.’ ‘you’re not my sister.’ ‘you’re a monster.’ their eyes screamed. ) It took what seemed like forever for her to finally land in her mother’s arms. Sonia didn’t remember how, never could for the life of her (for she passed out in exhaustion the moment she saw her mother was okay), but somehow they made it to a house inside the Ruins. What she did remember for sure, however, was waking up to the smell of butterscotch cinnamon pie and throwing out the golden flower crown Caitlin made for her.

And the fact she’d been scared to death of Toriel the first time they met (mostly because of Asriel), and she’d hidden under the dining table. (she laughs about it now)

Leto, however,…was nowhere in sight.

Later, when she was old enough to understand what death meant, Sonia would learn that her mother had died of a broken heart. Leto had left her with a dark blue rose on a light blue hair bow, something she’d gotten from her mother when she was six years old. And Sonia’s been wearing it ever since.

The moment she turned 20, Sonia left the Ruins (after an emotional goodbye from Toriel and the two sharing one last hug). That was when she met Sans and moved in with the Skelebros in Snowdin.

Now, she’s heard rumors about a human falling from the surface…


Towards Humans: She doesn’t trust them that much. The only human she likes is Frisk. (Don’t ask her about Caitlin)

Towards Strangers: She’s wary around them and avoids them unless they’re friendly.

Towards Friends: loyal, talkative

Strengths: her loyalty to her friends

Weaknesses: being made fun of, people poking fun at her eyes (hence the eyepatch), family being called monsters, being called Marston (she doesn’t want to have anything to do with Cole)

Flaws: She’s occasionally too loyal

Likes: Toriel’s pies, puns, Sans, spaghetti (she blames Papyrus & Undyne for that), being scratched behind her ears, listening to music, reading

Dislikes: her father, her friends getting hurt

Fears: losing her friends.

Battle InfoEdit

ATK: 8 (pacifist/neutral), 16 (genocide)

DEF: 7 (pacifist/neutral), 14 (genocide)

EXP: 21

LV: 6

POWERS/ATTACKS: Able to use blue, white, and yellow fangs (9 damage) & claws (6 damage). POWER: Fang over Claw (bites a side with ! on, followed by swiping her claws diagonally left to right) WEAPONS: Yellow magic, her claws & fangs, & toy gun

FIGHTING STYLE: She’s calm unless someone hurt/killed her friends. Then she’s more violent.


Friends With: Sans, Papyrus, Frisk, Toriel, Alphys, Undyne, Monster Kid, Napstablook, Temmie

Neutral With: Burgerpants, Mettaton, Gaster, Grillby

Enemies With: Chara, Flowey, Asriel

Family: Cole Marston (human; birth father), Leto Babiole-Marston (cat monster; birth mother), Caitlin Marston (human; older sister), Toriel (surrogate mother), human grandparents (unknown), monster grandparents (unknown)

Crush(es): Sans

Single, Taken, Or Talking (If the last two, with who): Single and ready to mingle

Other InfoEdit

Alignment: Neutral

Goals/Purpose: To become a singer and tour the surface

Job: Professional Napper, singer

Pages Edit

RP: willintowait