Toriel

 is the second character encountered in Undertale. She saves the protagonist from Flowey and guides them through the Ruins.

Appearance
's head resembles that of a white-furred Nubian goat, with droopy ears and short horns. She has a pair of visible fangs and long eyelashes; her irises have a slight red tint. Her body is anthropomorphic, with paws at the end of her limbs. She wears a long blue robe that displays the Delta Rune on her chest and is occasionally seen with her reading glasses on.

Personality
is a kind and motherly boss monster who genuinely cares for the protagonist and their well-being. While ultimately a benign figure, she has a harder side to her personality, as seen in her attempt to keep the protagonist in the ruins, and her cold treatment of Asgore.

She also has a playful side; she loves puns and bad jokes. She also enjoys cooking. Many of her recipes use snails as a primary ingredient, and her favorite food is snail pie. She's also known to bake butterscotch-cinnamon pie.

was considered to be the brains of the throne when she was queen, even stating a desire to be a teacher. By the time the protagonist reaches her house, she states that she has already prepared a curriculum for their education. In the game's credits, she is shown standing outside a school, and in certain Neutral Endings, she starts her own.

Main Story
Before the events of Undertale, she was married to King Asgore and had a son, Asriel. When the first human fell into the Underground, she adopted them as their child. The deaths of their two children pushed Asgore to declare war on humanity, and as a result, she divorced him, abdicated her throne, and retreated to the Ruins. Between then and the time the protagonist entered the Underground, she had seen multiple humans be murdered and their SOULs reaped by Asgore.

Neutral Route
At the beginning of the game, saves the protagonist from Flowey, healing any damage done by the murderous flower. After introducing herself, she guides them through the first few rooms of the Ruins. She encourages the protagonist to deal with monster encounters by talking to them, as opposed to acting violently.

She gives the protagonist the cell phone to keep in contact with one another, as she needs to run some errands further into the ruins. She tells them to stay where they are, only to be disobeyed. She calls the protagonist frequently as the protagonist goes through the ruins, and is about to call them again when she finds the protagonist at the entrance to her home.

She introduces the protagonist to their room and plans to raise the child as her own. After the protagonist pesters her about leaving the Ruins, abruptly leaves and is followed by the protagonist. As she goes deeper towards the exit, she explains that she plans to destroy it to prevent them from leaving, as all other humans who left had died.

At the end of the Ruins, tells the protagonist to prove themself strong enough to survive and fights them in a test of strength. She can be killed or spared; if spared, lets the protagonist go but tells them not to come back.

Sans tells the protagonist during their rendezvous, that he and have been friends for a while, bonding over their love of jokes and puns. Neither of them know each other's name or face, as they communicate through the door that blocks off the Ruins. Sans also says that asked him not to kill any humans he found. He remarks that if not for that promise, the protagonist would be "dead where [they] stand."

See Toriel Ending Tree.

True Pacifist Route
reappears just as Asgore and the protagonist prepare to fight, interrupting it with her fire magic, much like she does with Flowey at the start of the game. She explains the motive of her arrival was the realization that the protagonist would have to take a life to leave, and that she was trying to prevent such thing from the beginning. As the protagonist's friends come, she introduces herself to them and recognizes Sans's voice immediately. She tells the protagonist that while they may have to stay Underground with all their friends, they will live a happy life regardless.

Unfortunately, Flowey appears. Having absorbed the human SOULs, he binds and company with vines. When Flowey tries to kill the protagonist, is the first monster to intervene, using her fire magic to block Flowey's bullets. Her SOUL, along with every other monsters', is eventually absorbed by Flowey, allowing him to become Asriel. During the protagonist's battle with Asriel, appears as one of the Lost SOULs.

True Pacifist Ending
After the fight against Asriel concludes, she learns the protagonist's name, Frisk. She tells them that they are free to go through the Underground to talk to more of their friends. Meanwhile, Alphys upgrades Toriel's Phone, allowing her to send text messages.

Frisk leaves the Underground with and their other friends. As the others leave Frisk to begin their lives on the surface, asks Frisk what they will do now.
 * If Frisk decides to stay with, she remarks that they would have never left the Underground if they made that choice earlier, but that it was fortunate for them to take so long to change their mind. She understands Frisk has no place to go and is more than happy to care for them, for as long as they need. She takes their hand as they walk away together. At the end of the credits, there is a scene where brings a slice of pie to Frisk's room.

In the credits sequence, is shown welcoming the Monster Kid to a school, having opened a school and becoming a teacher.
 * Frisk may tell her that they "have places to go."  understands and is not upset to hear this. Before she leaves Frisk on their own, she tells them that she will "see [them] around." At the end of the credits,, Frisk and co. are shown together in a photograph.

In Battle

 * See Toriel/In Battle

Protagonist
genuinely cares for humans who fall into the Ruins, and the protagonist is no exception. is very protective of them. tries to keep the protagonist in the Ruins, as the other humans who left her care were killed by Asgore. If the protagonist spares her, she lets them leave the Ruins, but not before giving them a parting hug.

If the protagonist kills her during on the Neutral Route, she will use the last of her strength to give them a warning about what lies ahead. Although the protagonist is responsible for her death, she will show no contempt and maintains her motherly attitude before she dies. However, if the protagonist kills her when she's showing mercy, she will mockingly tell them how evil they are. In the Genocide Route, she asks them if they really hate her that much, and claim that the ones she was protecting by keeping them in the Ruins were the monsters and not the protagonist.

If the protagonist calls "Mother" it will surprise her, and states that if it makes them happy, then she heartily approves of it.

Calling on her phone in the Ruins and flirting with her makes her assume the protagonist is joking, if they do it again she says she's unsure whether their interest in her is endearing or pathetic. If they flirt with her after calling her "Mother," she will become uncomfortable, and calls the protagonist an "interesting" child. She will also mention this in the True Pacifist Ending.

If the game is reset, says that talking to the protagonist is like "meeting an old friend for the first time."

Asgore
Asgore is 's ex-husband. They were once extremely close, winning first place in the '98 Nose Nuzzle competition and being openly affectionate to the point where Gerson described them as "insufferable". She is the source of his nickname, "King Fluffybuns".

After Asgore declared war on humanity, left him out of sheer disgust. She is also frustrated by his meek unwillingness of following his plan and his hope for no human to ever come into the Underground. She also refuses his advances to reconcile; in the True Pacifist Ending, she calls him a "pathetic whelp." However, it is hinted that she still holds him in her heart, as evidenced by having his favorite flower in her room and still baking his favorite pie. Asgore is seen trimming a hedge near her school in the end credits, implying they have reconciled to at least some degree.

Flowey
does not seem to know Flowey very well but she doesn't have a high opinion of him after catching him attempting to kill the protagonist and knocking him away with a fireball. Flowey calls her an "old hag."

Sans
Although the two never meet in person until the end of the True Pacifist Route and the Family and Exiled Queen endings, where they both have become good friends. They started their friendship by telling jokes to each other through the door leading to the Ruins.

At one point, requested him that if a human were ever to come through the door, he'd keep them safe. Even though Sans hates making promises, he agreed to keep it. They continue to bond after the final boss fight in the pacifist run, texting Frisk multiple times as they walk through the Underground.

Name
's name is a play on the word "tu-torial", as she teaches the protagonist about how the game works. It is also similar in pronunciation to "toro", which means "bull" in Spanish.

When attempting to name the fallen human "", the response becomes "I think you should think of your own name, my child" and prevents the name from being used.

Trivia

 * Despite 's motherly nature, she is not above saying curse words:
 * In the True Pacifist Ending, she says "Who the hell is Sans?" before correcting herself with "Who the HECK is Sans?". This causes a surprised reaction out of Alphys.
 * Toby Fox stated that it is possible for to have said the "F-word."
 * once wore a flower-patterned muu-muu; other monsters complimented her by saying "nice muu-muu", but she assumed everyone was calling her a cow, so she never wore it again.
 * If the dummy's battle is ended by boring it, will stare in confusion before moving on as if the fight never happened.
 * If is spared, she heads to the flower bed at the beginning of the game, saying "Do not worry about me. Someone has to take care of these flowers". Her son says the same thing in the True Pacifist Ending Epilogue.
 * When Toriel asks your preference, butterscotch, or cinnamon, if you choose one, and restart the game, Toriel will remember that preference and ask you if that is it beforehand.
 * Even if Toriel is spared in Hard Mode, the Annoying Dog will still comment on how she should be dying despite the fact that the player didn't actually kill her.