Asriel Dreemurr

Asriel Dreemurr (typically /ˈæz.ɹiː.əl ˈdʒɹiː.məɹ/) is the biological child of Toriel and Asgore, and the adoptive brother of the fallen human, Chara. He serves as the "true" final boss of the True Pacifist route, and the hidden main antagonist of Undertale.

Appearance
Asriel's appearance is similar to his parents, Toriel and Asgore, with long ears, a snout, and visible fangs. In his initial form, he wears a green long-sleeved shirt with yellow stripes, and black pants.

God of Hyperdeath
This form is named directly in the game, where the "Check" option labels Asriel as "the absolute GOD of Hyperdeath!" The sclera of Asriel's eyes becomes black, his fangs become longer, and he has a pair of horns. He wears a long dark robe with white sleeves and the Delta Rune on the front, similar to Toriel's, with a large collar and shoulder pads. He also appears to be wearing a locket similar to the Heart Locket.

Angel of Death
While this form is not directly named, it resembles the Delta Rune, which looks like the "Angel of Death" from the prophecy. His body becomes more geometric, his horns longer, and his teeth sharper. He has a pair of wings that continuously change color, and his lower body becomes sharp and heart-shaped, much like Mettaton NEO, excluding the heart shaped aspect.

Personality
Before his death, Asriel was known to be a docile, unadventurous, and loving child. After being brought to life again by Alphys without a SOUL as Flowey, he became incapable of feeling joy, or love, implying that something without a soul has no feelings, leaving him bored and resentful. After temporarily regaining his compassion, he apologizes for his actions to Frisk and realizes the gravity of his actions as a flower.

Main Story
Before the events of Undertale, Asriel found the fallen human, who was the first human to fall into the Underground. They became his adoptive sibling and best friend. When the human died, their last wish was to see the Golden Flowers of their village, on the Surface. Asriel absorbed their SOUL, and the human carried their own body across the barrier to their home village. Asriel clarifies that he and his sibling shared control of their body after their SOULs had combined; he did not pick up the human's body, as the power was shared between the two, Chara picked up the deceased body.

The villagers assumed that the Asriel/Human fusion had killed the child, and they attacked. The Asriel/Human fusion, lethally wounded, and still refusing to fight back or kill six humans, the original plan, returned to the Underground and died. Once deceased, Asriel's dust spread across the garden, leaving his essence on it.

Later, Alphys injected determination into the first golden flower that had bloomed in the garden just before the queen left. Initial experiments on the flower vessel proved unsuccessful, and Alphys returned the vessel to Asgore. Once the vessel was replanted, Flowey awoke within the garden. Though Asriel's essence from the garden bed granted Flowey Asriel's memories, he soon found that neither his mother nor father could elicit any emotional response from him. He did not have a monster SOUL and was unable to feel love, joy, or compassion.

Neutral Route
Asriel does not appear during the events of the Neutral Route.

However, when the protagonist falls into the Garbage Dump, Asriel's sound bite can be heard during a memory of the fallen human's. The encountered monsters also tell his story during the walk in New Home, except for a few monsters such as Aaron.

True Pacifist Route


In the True Lab, the protagonist discovers that the fallen human and Asriel had worked together on a plan to get to the Surface and retrieve six more human SOULs. The human thought of the idea to poison themself with buttercup flowers so that Asriel could absorb their SOUL and go through the barrier. While the human was on their deathbed, Asriel informed them he did not think it was a good plan anymore; ultimately, this leads to him betraying his sibling and aborting their plan.

After restoring the elevator's power, the protagonist receives a phone call from Asriel, evidenced by the voice bite, mistaking the protagonist for his adopted sibling.

Flowey appears when the protagonist and their friends come together to stop the fight between the protagonist and Asgore. A vine from Photoshop Flowey appears, and it tangles and traps the protagonist's friends. More monsters show up, encouraging the protagonist to continue fighting. Flowey absorbs the SOULs of every monster in the Underground (except Napstablook and Mettaton), as well as the six human SOULs and transforms into Asriel.

Asriel greets the protagonist as  before he transforms into ASRIEL DREEMURR, God of Hyperdeath. He then informs the protagonist that he does not care about destroying the world anymore, and instead just wishes to reset the timeline, so everything unfolds again from the beginning.

He then says that his first form is just a fraction of his real power and transforms into the "Angel of Death." Asriel tells the protagonist that they will die in a world where no one remembers them.

The protagonist calls to the Lost Souls inside of Asriel's SOUL and reminds them that they are friends with the protagonist. After all Lost Souls regain their memories, the protagonist realizes that someone else needs saving. The protagonist calls their name, and a few sepia tone pictures display. The pictures are of Asriel and his sibling together when the human first fell to the Underground.

Asriel begins crying and reverts to his original form. He then realizes that the protagonist was not his adopted sibling, and asks what their name is. The protagonist will respond "Frisk." He tells Frisk how many other monsters love them, and apologizes to Frisk for hurting them. He then proceeds to destroy the barrier that keeps the Underground apart from the Surface and returns the monster SOULs to everyone.

He tells Frisk that he has to go; Frisk has the option to hug Asriel and comfort him before he leaves. As he is walking away, Asriel tells Frisk to take care of his parents for him.

Epilogue
Asriel is at the flowerbed where Frisk fell at the beginning of the game. He can only be spoken to immediately after his boss fight; if the player watches the True Pacifist Ending Credits and reloads the game, Asriel does not appear. Asriel speaks extensively to Frisk and offers them a different philosophy than his flower counterpart: "Don't kill, and don't be killed."

After the credits sequence, when reopening the game, Asriel returns as Flowey and begs  to "Let Frisk go" and allow everyone to live their lives.

Genocide Route
After the protagonist kills Toriel, Flowey tells them that they are not really human, and mistakes them for the first child, telling them that they are still inseparable after all those years.

When the protagonist reaches New Home, Flowey welcomes them and discusses his backstory as a flower and how he discovered his ability to SAVE. Near the end of his dialogue, he realizes that the protagonist will not hesitate to kill him, and he is frightened for his life. He rescinds his previous plans with the protagonist and tells them to leave him alone.

After the protagonist defeats Sans, they easily kill Asgore. Flowey destroys Asgore's SOUL and pledges himself to the protagonist one final time in an attempt to save his own life, revealing his true identity as Asriel in the process. He cries and begs the protagonist not to kill him, to no avail.

In Battle

 * See Asriel Dreemurr/In Battle

Protagonist
In the True Pacifist Route, Asriel mistakes the protagonist for the first human and calls them his best friend. After the final boss fight, Asriel realizes that Frisk is not the first human and asks what their real name is. He later tells Frisk, if they backtrack to the flowerbed, that he does not regret his decision of resisting his sibling and, ultimately, getting them both killed.

The First Human
Asriel found the first human when they fell into the Underground. He became their best friend after helping them, and then the first human's brother after Toriel and Asgore adopted them.

After the human carried their own body to the Surface, Asriel resisted his sibling's desire to use their full power, and humans fatally wounded them. With the first human's empty body in his arms, Asriel returned to the Underground and collapsed. His dust spread over the flowerbed in New Home as he died. Even after becoming Flowey, he could not think of a world without them, as they are the only person that understands him and that is unpredictable to him. The first human, however, wants to kill Asriel out of revenge for ruining their plan and getting them both killed, and succeeds at the end of the Genocide Route.

Asgore
Asgore is Asriel's father. When Asriel first woke up as Flowey, Asgore was the one to find him. Asriel informs Asgore of his identity, hoping to feel something and possibly turn back into his original form. However having lost his SOUL, he discovers he feels nothing for Asgore any longer. Asgore believes that letting the protagonist escape the Underground with his SOUL is what Asriel would have wanted.

Asriel's habit of saying "gosh," "golly," and "howdy" may come from Asgore.

Asgore is unaware that Flowey is Asriel.

Toriel
Toriel is Asriel's mother. In older timelines, after failing to feel anything with Asgore, he had turned to Toriel in hopes of feeling love again with her. This ultimately failed, as he could not love others without a SOUL.

Toriel is, like Asgore, unaware that Flowey is Asriel.

Alphys
Alphys unintentionally created Flowey as a result of the determination experiments, but there is no indication that she knew Asriel in life.

Trivia

 * Asriel's name has several possible meanings or origins.
 * Asriel's name is a combination of his parents' names, Asgore, and Toriel, likely stemming from Asgore being terrible at naming things. An interesting thing to note is that this follows Anglo-Saxon naming traditions, from where the English language imported names like Albert, Edgar, or Wilfred.
 * "Asriel" might be derived from "Azrael," the God of Death in Jewish and Islamic mythology. Gerson mentions an Angel of Death in his explanation of the Delta Rune prophecy.
 * "Asriel Dreemurr" is an anagram of "serial murderer."
 * "Dreemurr" is similar in pronunciation to "Dreamer," alluded by the ACT "dream" in his battle, and his leitmotif "Hopes and Dreams."
 * "Asriel" is also a name of Hebrew origin that means "Helped by god." This might be a reference to Asriel being miraculously saved and turned to a flower after dying, or helping Frisk by breaking the barrier with his god-like powers.
 * His name and appearance could have also been inspired by Sariel, from the game Touhou: Highly Responsive to Prayers. Their names are similar, and this character's outfit resembles God of Hyperdeath's (it also bears a symbol similar to the Delta Rune). Sariel is also an angel of death.
 * When attempting to name the Fallen Child "Asriel," the response becomes "..." and prevents the name from being used.
 * Both Undyne the Undying's armor and Mettaton NEO's body closely resemble Asriel's Angel of Death form, displaying a heart on the chest (and both gloves in Undyne's case), large, spiked shoulder pads, and, in Mettaton NEO's case, enormous, vibrant wings.
 * Napstablook and Mettaton are the only monsters whose SOULs are not absorbed by Asriel.
 * If the game is hacked, it is possible to spare Asriel Dreemurr during his boss fight, and the protagonist will be left on overworld where they left off: in front of Asgore, with the six souls. Nothing will happen, and the protagonist can walk around and even above the barrier.
 * It is possible that Asriel inherited his father's trait of being bad at coming up with names, as when he is in his flower form he names himself "Flowey."
 * Flowey is the only character that begs for the protagonist not to kill him.