Neutral Route

The Neutral Route is one of the three primary routes in Undertale. In this route, the final boss is Photoshop Flowey, though after fighting him once (without performing a True Reset or a Genocide Route), Flowey only destroys Asgore's SOUL and his fight is skipped, as he knows the SOULs would revolt again.

On a True Pacifist Route, the protagonist must reach one of the Neutral Endings to unlock the quest line leading to the True Pacifist Ending.

Method
This ending occurs when the requirements for either the True Pacifist Route or a Genocide Route have not been met, or if the protagonist is on the True Pacifist Route on their first playthrough. Essentially, either at least one monster must be killed, but Genocide mustn't be initiated, or the player must complete the game without befriending the necessary characters.

There are many versions of this ending, all consisting of Sans calling the protagonist's Cell Phone and leaving a message telling the protagonist of the Underground's fate. However, the content of the phone call is based upon the actions that the protagonist has made throughout the game.

Neutral Route Epilogue
In all of the neutral route endings, Alphys says that the protagonist must kill Asgore and take his SOUL because a human SOUL alone cannot pass through the barrier. Consistent across all Neutral Route epilogues:
 * Asgore is killed (by the protagonist, Flowey, or by suicide)
 * Flowey is defeated
 * The six human SOULs are lost
 * The monsters remain trapped behind the barrier and assume that the protagonist escapes the Underground.

After the brief, lackluster credits of the Neutral Route, Sans calls the protagonist's Cell Phone to leave a message. The phone call then branches into their respective ending.

Toriel Ending Tree

 * Requirements: Toriel is spared.

Toriel has returned to her throne to rule over the Underground and has instated a policy of non-hostility towards future humans that fall into their world. This ending then branches into one of three variants: the "Family Ending," the "Betrayed Undyne Ending," or the "Exiled Queen Ending."

Family Ending (Flawed Pacifist)

 * Requirements: The protagonist has befriended Papyrus and Undyne, and has defeated Asgore.

Despite the disappearance of the human SOULs and Asgore's tragic death, Toriel rouses the spirits of the Underground's inhabitants and tells them not to give in to despair. Sans likewise encourages the protagonist never to give up.

The call passes to Papyrus, who proudly proclaims his new position as " CAPTAIN OF THE ROYAL GUARD. " This turns out to be a figurehead position, as the Royal Guard (whose primary responsibility was to keep watch for human SOULs) has in fact been disbanded. His only real duty is tending to the garden of the New Home castle.

The former Royal Guard captain Undyne then enters the call and explains that she has found new work as Alphys's lab assistant. She has also been appointed to be the gym teacher of Toriel's new school; she boasts that she can bench-press seven children. The next part of this ending varies depending on whether the protagonist has dated Alphys.


 * If the protagonist has not dated Alphys: Alphys becomes even more reclusive. However, Undyne confidently states that she can help Alphys work through whatever is bothering her. Undyne also reminds the protagonist that she and the other monsters sacrificed a great deal to help the protagonist return to the human world; for that reason, the protagonist should appreciate life on the Surface to the fullest, and make the monsters' sacrifice worthwhile.
 * If the protagonist has dated Alphys: Undyne ropes her into the call. Alphys first reassures the protagonist that Mettaton is doing okay, and then goes on to mention that she is searching for a new way to free the inhabitants of the Underground. She is working harder than ever, mostly because Toriel is a much stricter supervisor than Asgore ever was.

At this point, it occurs to Undyne/Alphys to ask Toriel to join the conversation; however, Toriel simply tells her that she is busy, not realizing that the protagonist is on the other end of the line. Papyrus and Sans joke that Toriel would probably tie up the line for hours if she only knew the protagonist was on the phone, and that they " HAVE THE MERCY TO SPARE YOU FROM HER ." Undyne, and Alphys if she was dragged into the call, then suggest(s) calling back anytime as she would love to talk.

The call ends with Sans mentioning that the phone is low on batteries, and everyone says goodbye.

Betrayed Undyne Ending

 * Requirements: The protagonist did or did not befriend Undyne and killed less than ten monsters, or killed Mettaton. Undyne cannot be befriended if the protagonist had killed monsters before initiating her hangout.

Toriel tries her best to tell the inhabitants of the Underground not to give up even though their situation is pretty grim. Sans also tells the protagonist that they should not give up either. Papyrus then joins the call and take over for the remainder of the call. Papyrus states that Undyne has it rough since she lost her job and her house, then says that he and Sans are taking care of her now. Sans has hired her at his illegal hot dog stand in Hotland, except Undyne hates working there. The rest of the phone call branches into three different paths depending on what the protagonist has done. Befriending Undyne simply causes Undyne to hate the protagonist more than ever since they betrayed her trust and killed someone.
 * If the protagonist has not befriended Undyne: Undyne simply blames the protagonist for Asgore's death. Papyrus mentions that she has the plan to cross the barrier and beat the protagonist up. Papyrus thinks her plan is impossible but also hopes that it is not since it would mean meeting with the protagonist again, even if it does mean fighting them. Papyrus then says to keep the protagonist's fingers crossed and to keep in touch to make their plans easier.
 * If the protagonist killed Mettaton regardless of befriending Undyne or not: Undyne is devastated since Asgore and Alphys are gone. She says things like "I couldn't protect her," and it is hard to get her to do anything. Papyrus suggests that she goes after the protagonist to get revenge, but Undyne says "Revenge won't bring anybody back." Of course, Papyrus is unaware of their deaths, so he asks the protagonist to bring her friends back since Undyne is not doing so well.
 * If the protagonist has befriended Undyne and killed monsters afterward: Undyne hates herself for becoming friends with the protagonist because they had murdered someone shortly after they had formed a friendship. She feels hurt, betrayed, and angry at herself, and does not understand why she let herself be friends with the protagonist. She says that she knew what humans were like but failed to resist becoming friends, because of her mistake more people got hurt. Papyrus then suggests the protagonist to " PROBABLY NEVER COME BACK HERE " since Undyne would destroy them and even the queen cannot stop her.

The call ends with Papyrus saying goodbye (forever, if in the third branch) to the protagonist.

Exiled Queen Ending

 * Requirements: The protagonist has also killed ten monsters, Papyrus, or Undyne.

Toriel's new policy was met with severe backlash since the protagonist has killed Papyrus, Undyne, or countless monsters in the Underground, so a rebellion was formed to overthrow the queen. Sans mentions that he decided to accompany Toriel when she returned to the Ruins and brought her books from the library in Snowdin so that she does not have to read the same ones.
 * If Undyne is alive: Undyne gets enraged that Asgore was killed, and if Mettaton is dead, Alphys disappears, nowhere to be found by the other characters (it is possible that she commits suicide in the True Lab). Undyne spearheaded the revolutions and banished Toriel back into the Ruins. Sans comments that Undyne seems to be more vehement about destroying humanity than Asgore was.
 * If Undyne is dead: Toriel just peacefully resigns and returns to the Ruins after hearing about the rebellion, causing the Underground to become an uneasy and hopeless anarchy.
 * If Papyrus is alive: Papyrus also accompanies Toriel in the Ruins and even plays games with her. Both Papyrus and Sans have also convinced Toriel to leave the Ruins sometimes, as long as either of them stay behind and keep watch for humans. Papyrus says that he loves to stand in for the Queen and is practicing to become a great mom when they come (probably due to the Greenlight trailer where Papyrus asks "IS IT ME? AM I THE MOM?" ). Sans ends the call hoping " things are better " wherever the protagonist is.
 * If Papyrus is dead: Sans calls Toriel a good roommate and mentions how she sometimes talks about how they would like to see the protagonist again. Sans does not have the heart to tell Toriel that they killed Papyrus because she protected them, then ends the call with " never come back here. you are not welcome. "

Undyne Ending

 * Requirements: Toriel is dead but Undyne is alive.

Undyne becomes the ruler of the Underground and enforces a policy to destroy all humans who enter. She plans to wage war on humanity, has militarized the Underground, and personally plans to destroy the protagonist. Sans mentions not being able to reach Toriel and, if Papyrus is dead, implies that she has been killed and that the protagonist is responsible, and warns them to watch themself as " things are lookin real bad for you. "

However, if Papyrus is alive, Sans simply says that Toriel might not be feeling well, allowing Papyrus to interrupt the call and tell the protagonist that Undyne has appointed Papyrus to "The Most Important Royal Position," which is a figurehead position where he stands around and looks cute, but he is proud of it. Papyrus says that the protagonist should come and visit, though he also says that Undyne will probably kill them if they do, but says that they should risk it.

Regardless of Mettaton's status, it has no effect on the dialogue of this ending.

Mettaton Ending

 * Requirements: Toriel and Undyne are dead, but Mettaton is alive.

Mettaton becomes ruler of the Underground since Undyne disappeared, and establishes a dystopian society in which he brainwashes the entire Underground with his television show. Sans mentions that he became his agent and then hands over the phone to Mettaton.

Mettaton establishes a policy on humanity that any human that falls can join his fan club for free. He says that he has created a statue of Alphys, but then goes on to say that he was "not the greatest to her." He says that he was going to apologize to Alphys and ask her to help him rule, but could not find her, and emphasizes "TRUST ME. I LOOKED." It is implied that Alphys either commits suicide or runs away (likely into the True Lab). Mettaton then asks the protagonist to think of him always and ends the phone call there.

If Papyrus is alive and befriended, he then joins the call to mention that he has become Mettaton's second agent. He says that things have gotten a lot better since the protagonist came (excluding the fact that everything sucks and anyone who does not worship Mettaton goes missing), but misses Undyne and asks the protagonist to say "hi" if they see her.

Papyrus Ending

 * Requirements: Toriel, Undyne, and Mettaton are dead, but Papyrus is alive.

By process of elimination, Papyrus became the ruler of the Underground, though Sans does most of the work. Sans tells Papyrus that Asgore, Alphys, Mettaton, and Undyne are on vacation. The Underground is improving; productivity is up, and Papyrus cooks everyone spaghetti. The human policy instituted is that humans cannot be judged to be all good or all bad. Either way, they get puzzles. Once Sans leaves, Papyrus expresses distress on his new responsibility as the ruler when people " WANT TO GIVE UP " and how he misses all his friends; he mentions how Undyne never picks up his calls, and that she must be really enjoying herself on vacation. However, Papyrus reassures the protagonist that he is determined to " MAKE EVERYONE GIVE UP GIVING UP ", and hopes to get out of the Underground and hang out with the protagonist again.

Dog Ending

 * Requirements: Only Toriel, Papyrus, Undyne, and Mettaton are dead. All other monsters are alive, Glyde and So Sorry included.

A small, white dog becomes the president of the Underground. The dog sleeps on the throne and does absolutely nothing. Strangely, this is the best life for everyone. Oddly enough, Sans does not mention the protagonist killing Papyrus in this phone call and thanks the protagonist for the results. "Dogsong" plays during the call just like in the Impossible Ending.

Leaderless Ending

 * Requirements: Toriel, Papyrus, Undyne, Mettaton, and at least one (but not every) non-boss monster have been killed.

The Underground is leaderless and less crowded. Things have gotten pretty bad. The mood is somber, and people feel as if they are just going to die in the Underground, trapped in the dark. Sans says he is not the ruler because he is not cut out for something like that, and he likes to take it easy (which is a joke; he says this is what happens when people like him decide to take it easy). Sans then tells the protagonist to " go to hell. " If less than 20 non-boss monsters were killed, Sans says " see ya. " instead.

A variant of this, where all encounters (but not all possible monsters) were killed, is known as the No Mercy or Neutral No Mercy Route. This offers no different dialogue than any other Leaderless ending.

Alphys Ending (Near Genocide)

 * Requirements: The protagonist followed the Genocide Route requirements throughout Waterfall but aborted the route during the travel through Hotland.

The protagonist does not encounter Alphys during this route, as the ending requires killing Undyne the Undying, which preempts the protagonist's meeting with Alphys in Hotland. After Sans finds the protagonist's contact information, he hands the phone over to Alphys, who has now become the new ruler of the Underground.

Alphys explains that after hearing Undyne's last words, her resolve was strengthened, and she proceeded to evacuate the remaining monsters in the Underground to a safe location (presumably the True Lab). The survivors lauded her as a hero and elected her as the new ruler. Despite her confidence in her governing abilities, she remains anxious around people. After mourning the loss of her friends, she ends the call saying that she should have killed the protagonist when she had the chance.

Impossible Ending (Dirty Hacker)

 * Requirements: The protagonist has somehow met none of the above requirements or hacked the game.

As "Dogsong" plays in the background, Sans says that he has no idea what the protagonist has done to get this ending, and explains that the call is an error-handling message. He goes on to suggest contacting the developer so they can fix the game or add another ending. Sans then says " chances are, though... you're just a dirty hacker, aren't you? yeah, get outta here. " then simply hangs up.

Flowey's Parting Words
After the phone call, if the protagonist had spared Flowey, he appears to talk to the protagonist. His dialogue depends on the protagonist's actions during the neutral route.
 * If the protagonist had killed some monsters, Flowey wonders if killing is necessary and asks the protagonist if they can reach the ending again without killing, and he will not kill Asgore, and maybe the protagonist will have their "happy ending." Flowey remarks that he intends on watching before leaving.
 * If the player reloads their SAVE and triggers the neutral ending a second time, Flowey assumes the protagonist wants to be friends with him. He proceeds to insult the protagonist, saying that he only cares about one person but ultimately truly does not care about them.
 * If the player reloads their game and triggers the neutral ending a third time, Flowey asks if the protagonist wants to start the Flowey Fan Club. He then tells the protagonist to talk to Papyrus about it, as he started one multiple times. Flowey goes on to say that Papyrus was one of the better characters to mess around with and took a long time to get bored of him.
 * If the player reloads their game and triggers the neutral ending a fourth time, Flowey jokes about the Flowey Fan Club. Flowey then warns the protagonist not to let Sans know anything about them, as he caused Flowey's fair share of resets.
 * If the player reloads their game and triggers the neutral ending a fifth time, Flowey notes that the protagonist is simply bored and just wants to see what Flowey has to say. He then refuses to talk to the protagonist any further.
 * If the player reloads their game and triggers the neutral ending a sixth time and onwards, Flowey simply asks if the protagonist has anything better to do.
 * If the player resets their game and reaches the neutral ending again without kills, Flowey notes that the ending is still the same and tells the protagonist that their choices do not seem to matter. He then tells the protagonist how to achieve a real happy ending: befriend Papyrus, Undyne, and Alphys.
 * If the player resets their game and reaches the neutral ending again with kills, Flowey agrees that killing is fine, but proceeds to scold the protagonist for only going halfway.
 * If the player resets their game, reaches Asgore without kills, then kills Asgore at the end of the fight, Flowey scolds the protagonist that they are trolling themself because all they had to do was befriend Papyrus, Undyne, and Alphys.
 * If the protagonist killed no one, Flowey wonders why the protagonist let him go and why they are being so nice despite leaving the monsters still in despair. He then tells them a way to get a better ending by befriending Papyrus, Undyne, and/or Alphys.
 * If the protagonist befriended all the key characters without exploring the True Lab, Flowey tells the protagonist to see Alphys, as their date has just begun.
 * If the protagonist aborts the Genocide Route, Flowey complains that they were so close to real victory, but the protagonist screwed it up. He begins to wonder if they wanted revenge against him but quickly insinuates that they wanted to see the monsters happiness before tearing it away. He then says that he will be "waiting for you."

Trivia

 * How exactly the protagonist leaves the Underground is unknown, as Flowey destroyed Asgore's SOUL, and Flowey doesn't have a SOUL so the protagonist only had a human SOUL; thus, they should not have been able to leave the Underground.