Asgore Dreemurr

Lord Asgore Dreemurr is the ruler of the Underground, and its denizens, monsters. He is the ex-husband of Toriel, the father of Asriel Dreemurr, and the final boss of the neutral route.

Appearance
Asgore is a Boss Monster that resembles a large goat or possibly a type of dragon since he doesn't have hooves. He has an incredible shoulder span, a blond mane, blond beard, and two curving horns. He appears to wear a suit of armor as well as a blue cape with yellow pauldrons. As shown by the size of his armor in-battle, he sports an intimidating stature. Among his many features, Asgore also dons a small crown atop his head.

Personality
He is depicted as a kindly and easygoing family man; this is shown through his dialogue with Frisk during their encounter in the Neutral and the True Pacifist Route, as he attempts to be as kind as possible despite knowing that he will ultimately need to take their soul, going so far as to make small talk. He is an exceptional warrior, but is deeply uncomfortable with the act of killing. He enjoys gardening in his free time.

Most other monsters in the Underground consider Asgore to be an excellent king, if bad at naming things. Toriel, however, criticizes him as an indecisive and weak ruler, preferring to keep the monsters trapped underground waiting to be saved rather than going out and taking the souls he needed to break the Barrier.

All that has happened to him prior to the events of Undertale has left him very depressed. During Undertale, he has several difficult decisions to make, which he disagrees with morally, but feels compelled to enact. This burdens him heavily. By the time the player fights him, he is aware of the horrific things he did to try and save his people, and simply hangs his head in shame while he fights.

Main Story
Asgore and Toriel were originally married as King and Queen of the Underground, after being cast out from the Surface after the War. They eventually had a son, Asriel, as well as a second adopted child, the first human to ever fall through the Barrier. However, they eventually grew sick and died, all while Asriel was still young. Asriel ended up forming with the human's soul, and carried them past the Barrier back to their village. He sustained heavy attacks from the humans on the surface and ended up dying when he returned to the Underground.

This tragedy drew Asgore to the conclusion that all humans are dangerous, and decided to kill and harvest the soul of any human that falls through the barrier, so that he could gather the Seven Souls to become strong enough to destroy the barrier. Toriel was appalled by this grotesque decision, and forfeited her right as queen, divorced Asgore, and went to live in the Ruins, where she would care for any humans that fell through the barrier.

Between then and the start of the game, six additional humans fell through the barrier on Mount Ebott into the ruins; Asgore eventually reaped all of their souls and kept their bodies in his castle.

Neutral Route
After travelling through New Home and arriving in the Throne Room, Asgore greets the player. He comforts them as he brings them to the barrier, where he gives the player a chance to turn back if they have anything left to do before the fight. Asgore does not mind the delay, admitting that he himself is not ready either.

When the player is ready to fight Asgore, he tells the player that it was nice to know them. He then draws his weapon and destroys the MERCY button before starting the battle.

Fighting Asgore is the only way to end the battle without dying.

Much like with Toriel, attacking Asgore when he is at low HP will deal significantly greater damage. However, he survives the attack with a small amount of health remaining and kneels in defeat, talking to the protagonist about his declaration of war against humanity, admitting that he only wanted to give the monsters hope by continuing the war, and asks them to take his soul.

The player is given the choice of killing Asgore by selecting the FIGHT button, or sparing him by selecting the damaged MERCY button. Either way, Flowey steals the six human souls that were revealed prior to the fight. The protagonist deals with Flowey (first against him as a boss, then by finishing him off or sparing him), passes through the barrier, and escapes the underground alone. Asgore's death has a serious impact on the monsters.
 * If he is spared, Asgore is surprised that the protagonist would remain in the Underground, and offers to take care of the protagonist. Flowey appears and finishes Asgore off, both body and soul. He then mocks the protagonist that they still failed to learn that this is a 'kill-or-be-killed' world.
 * If the player kills Asgore, he dies smiling. Before the player can take his soul to be able to pass through the barrier, Flowey lands the final blow, shattering Asgore's soul. He tells the protagonist they finally realized that this is a 'kill-or-be-killed' world.

After ending the game, loading and fighting Asgore again has a significant difference at the end of the battle; if spared, Asgore fatally wounds himself, offering his soul to the protagonist so that they may escape and seek a way to destroy the barrier from the surface. However, before the protagonist can do anything with Asgore's soul, Flowey appears again and destroys his soul.

True Pacifist Route
When the throne room is reached, Asgore greets the Protagonist, and comforts them as he brings them to the barrier, where he gives them time to finish anything they still wish to do before fighting him. He then initiates combat with the player, but is interrupted by Toriel, who states how awful it is that he could seek to hurt an innocent creature such as the Protagonist. Then the other Bosses which the player has befriended arrive, and begin conversing, until Flowey appears, having stolen the six human souls, and begins to promptly steal the souls of the Bosses as well.

Flowey, fit with all of those souls, returns to his original form - Asriel Dreemurr. He then battles the player. After the battle is over, and the Protagonist is victorious, they convince Asriel to stop his plans, leading Asriel to destroy the Barrier and release the souls which he took into himself.

Asgore can be seen finally in the epilogue, asking the Protagonist if they would become the ambassador for monsters to humanity on the Surface. He is also shown trimming a hedge in front of Toriel's new school, implying they have reconciled to some degree.

Genocide Route
When the throne room is reached, Asgore makes a comment that implies that Flowey has spoken to him prior to the player's arrival, not recognizing them as the human he seeks. The player initiates combat and goes on to deplete his entire health bar with a single blow. Flowey returns to land the final hit as an attempt to appear loyal and useful to the player, and confides to them his true status as Asriel through morphing his face. However, this fails and Flowey is promptly killed.

In Battle
Asgore mainly attacks with fireballs and his trident. His attacks include: Asgore's attacks become faster as the battle goes on, but none of them can kill the player unless they're already at 1 HP - otherwise, the player's HP will only drop as low as 1.
 * Several waves of small fireballs from the top of the screen, which move in curving patterns. The player must maneuver their soul between the waves as they undulate.
 * Smaller waves of small fireballs that move down the middle of the screen, interspersed with massive clouds of projectiles that cover entire sides of the screen. Dodge the small waves, and get out of the way when a box marked with "!" appears
 * Partial circles of fireballs that gradually spiral in around the bullet box. Find the gaps in each ring and move through them in sequence, but be careful - some of them spin faster than others.
 * Moving his hands along the sides of the screen, leaving behind large fireballs that move towards the player's soul after a moment. Stay out of the hands' way and wait for the fireballs to begin moving before getting out of their way - they home in on the spot your soul was when they began moving.
 * Firing rings of large fireballs from the top of the screen, gradually moving from one corner to the other. Weave between the fireballs as they come.
 * Sweeping strikes of his trident that hit the entire bullet box. Before this attack, Asgore's sprite blacks out, and light flashes over his eyes - watch the color of the gleams to know what combination of orange and blue attacks he'll use, then react accordingly.

There are two known ways to lower Asgore's attack and defense: If you die to Asgore and then use the "Talk" action in the subsequent attempt, you'll get the following text: The dialog changes ("killed you twice, etc") until you get to five deaths, After five deaths the dialog will change to: After ten deaths the text becomes: When considering that Asgore has destroyed the player's MERCY button, it is plausible that he would know about the SAVE system as well, just as his longtime friend Gerson knows about how shopkeepers are invulnerable in their shops due to the game UI.
 * Consume Toriel's pie in his boss fight. This reminds Asgore of her and lowers his attack and defense.
 * Talk to him three times. This causes Asgore to remember something, lowering his attack and defense.
 * "You tell ASGORE that he's killed you once before. He nods sadly."
 * "You tell ASGORE that he's killed you five times. He nods grievously."
 * "You tell ASGORE that he's killed you too many times to count. He nods pitifully. "

Toriel
His ex-wife, he wishes to befriend her, which she refuses. Before they separated, they used to be "insufferable together", as described by the Turtle Shopkeeper in Waterfall. They ultimately fell apart after the deaths of their children. In addition to general moral objections to war, Toriel became disgusted by his overall wish-washiness in his decision making; while he had the resources to solve the problem immediately, he instead chose to try not to kill anyone by waiting for humans to fall into the underground, secretly hoping no other human will come along so that no one will die, hence prolonging the suffering of the monsters in the underground.

Undyne
Undyne mentions to the player that when she was younger she met Asgore in person and challenged him to fights. After Asgore defeated Undyne several times, Asgore offered to train her, and praised her when she finally managed to knock him down during practice. Undyne mentions that she knows Asgore's favorite type of tea and that he often gets marshmallows stuck in his beard when he tries to drink hot cocoa, implying that he often comes to visit her home.

Trivia

 * Asgore's last name, "Dreemurr" is an anagram of murderer.
 * In addition, when pronounced, "Dreemurr" sounds like "dreamer".
 * Also, Asgore has the word 'gore' in it.
 * Asgore wields a red trident during his fight. Being a goat-like monster with a red trident, it is a possible reference to Satan.
 * Asgore, as seen in the scene before the battle with Asriel and the ending, seems to still have a complicated relationship with his ex-wife Toriel.
 * His favorite kind of tea is Golden Flower Tea, as stated by Undyne.
 * Asgore is also known as King Fluffybuns, a nickname given to him by Toriel. This nickname is also used by the Turtle Shopkeeper.
 * Asgore has no flavor text when "Check" is used during battle.
 * The flavor text during the battle is limited: after "ASGORE attacks!", the flavor text is solely "..." until Asgore reaches low HP.
 * During Asgore's Boss battle, his sprite is designed to appear as either Asgore looking down in shame or concealing every feature but a maniacal grin in shadow, depending on how it's viewed. it also seems to show his hair in front of the crown, despite the normal sprite showing his crown in front of the laid-back hair. This may be a design error or a misinterpreted perspective. it has been found out though that it is merely the eye shadow caused by the brow-line.
 * By analysis of the multiple crumpled up pie recipes found in New Home, it can be assumed that after Toriel left him, Asgore attempted to recreate the way her pies tasted - though he could never truly replicate it. This is further supported by his reaction to the player eating Toriel's cinnamon-butterscotch pie during the fight.
 * Asgore's inability to kill the player unless their HP is already at 1 may be another sign of his reluctance to fight - he deliberately holds back until even his weakest attack becomes lethal to the player.
 * The name of the song that plays just prior to Asgore destroying the Mercy option, "Bergentrückung", is a German word referring to a mythological motif in which a heroic figure dies and their soul moves on to rest within a mountain (or other location), leading to what can be referred to in English as "king under the mountain". Combining the two song titles that play during the fight, they could be read as "king under the mountain, ASGORE", which describes the character well.
 * Since there is a flavor text that mentions a Santa costume, one can assume that Asgore is the Santa of the monster world that leaves the presents under the tree in Snowdin.
 * Asgore has eternal life, since Boss Monsters only age when their children do, and according to Gerson, he will most likely stay stuck at the same age forever. This means that Asgore takes up a similar role to the Gods of Greek Lore, being all-powerful but not immune to injury.
 * If you type "Asgore" for the character's name, the response becomes "You cannot." and prevents you from using the name like any other boss monsters (Minus Papyrus).
 * Asgore's red trident bears a visual similarity to the Spear of Longinus from the 1995 anime Neon Genesis Evangelion.