Endogeny
Endogeny (JP: わんさいぼう) (known in battle simply as "Amalgamate" before its spare conditions are met) is an Amalgamate found in the True Lab, where it is first disguised as floating debris in the fan room. It is the first Amalgamate to be introduced to the protagonist as one.
Endogeny is composed of the determination-filled SOULs of several dog monsters, including the parents of Dogamy and Dogaressa and other miscellaneous family members of Doggo, Greater Dog, and Lesser Dog.
Endogeny takes the vague shape of a large canine, with two pointed ears atop its "head" where instead of a face it only has a single orifice. Its wide body has six visible digitigrade legs, which form the silhouettes of five smaller canine or feline creatures between them. The silhouettes between its legs gain satisfied faces when it can be spared. The nature of one of its attacks combined with some of its flavor texts might suggest it may possess some form of propulsion on its body, such as a rocket. Additionally, its wet facial hole stops dripping when contented into being spareable. It is the only Amalgamate that looks similar to its overworld sprite. In the overworld, it appears to have a slightly yellow hue.
Endogeny displays the same excited behavior many of Undertale's dogs do, but seems to be unaware of the damaging nature of its enormous weight and powerful body, much like the Greater Dog. It exudes a fluid from its single orifice, which becomes a "happiness froth" when the Endogeny is excited.
Like all other members of its family, Endogeny's name contains the word dog in it. The name may be derived from the word endogenous, which means "having an internal cause or origin", sometimes in the context of families and/or the creation of ethnic groups. This refers to Endogeny containing multiple members of a single family and, in the Pacifist Route, all the Amalgamates being accepted as a new kind of monster.
In the Japanese localization, Endogeny is named "わんさいぼう", a wordplay on "単細胞" (meaning "single cell") and "わん", the onomatopoeia for barking.
After reaching the right end of the ventilation fan room in the True Lab the protagonist can press a switch to activate the ventilation fans. The ventilation fans blow various white pieces in the air into a white ball with a smiley face, which subsequently falls to the ground and turns into Endogeny. Endogeny then starts moving towards the cornered protagonist, and touching it starts the encounter.
At the end of the True Pacifist Route, it can be seen with most of the other dog characters, revealed to be its family, outside the Snowdin Library. When interacted with it imitates the signature sound and (perhaps weakly) facial expression of Greater Dog, who probably inherited these traits from one of the members of Endogeny. Its yellow text in the ending credits lists it, along with the other Amalgamates, as living with its family, implying it continued to spend its time with the other dogs.
- A sprite resembling the Annoying Dog (but with the Endogeny's orifice for a face) retracts its legs and reveals a rocket underneath its tail, using it to fly towards the SOUL in a straight line several times before the attack ends. This attack is capable of exiting the boundaries of the bullet board.
- The dog appears to the right of the screen, first faceless but then developing the orifice. Then it begins to move up and down while firing backward-facing arrows towards the SOUL in a random pattern.
Endogeny can be spared by using Beckon, Pet, Play, Pet, and Pet ACTs. The closer the protagonist is to sparing Endogeny, it vibrates more intensely, its orifice opens and closes faster, and the battle music plays faster. When Endogeny becomes spareable, the music is overlapped with a slowed down version of Dogsong.
Endogeny's battle shares many similarities with Greater Dog's, including the spare method and the spare conditions met flavor text. Unlike the Greater Dog, ignoring Endogeny has no effect.
The Hush Puppy can be used to pacify and spare the Endogeny immediately (making it fade prematurely before its contented version is shown), as can the Stick (in a similar fashion to other dog monsters). After using the Stick or Hush Puppy, however, the regular set of ACTs still has to be carried out to achieve the yellow text in the credits for the Amalgamates, though using one of these items first makes this task easier, as it prevents Endogeny from attacking.
- It's unclear how many dogs this counts as. [Check]
- It's the Amalgamate. [Encounter]
- Amalgamate is watching you intently. [Neutral]
- It smells like a bunch of dogs. [Neutral]
- Amalgamate is waiting for your command. [Neutral; unused]
- Amalgamate is too far away to pet. You just pet the air. [Pet before Beckon]
- You pet the Amalgamate. [Pet; unused]
- Amalgamate is not excited enough to play with...? [Play before Beckon and Pet]
- You play with the Amalgamate. [Play; unused]
- [Beckon]
- You call the Amalgamate.
- It bounds towards you, flecking a strange liquid from an orifice.
- Amalgamate is hovering close, looking for affection. [After Beckon]
- The Amalgamate's feelers rotate quickly. Nothing else happens. [Beckon #2+]
- You try looking away, but it seems to appear everywhere you look. [Ignore]
- [Pet after Beckon]
- You pet the Amalgamate. It convulses rapidly... Then calms down.
- It rests quietly on your lap for a moment...
- Zzzzz...
- Suddenly, it shoots away and crawls wildly on the walls!
- Amalgamate is striking the wall with its claws. [After Pet and Beckon]
- [Pet #2 after Beckon]
- You try to pet the Amalgamate but your hand phases through it.
- It must not want to be pet for now.
- [Play after Pet and Beckon]
- You throw your weapon into the corner of the room.
- The Amalgamate brings it back to you... Proudly?
- You repeat this process a few times.
- Now Amalgamate is very tired... It leans its dripping, amorphous body on you...
- Amalgamate is twitching affectionately. [After Play and Pet and Beckon]
- Amalgamate seems too tired to play. [Play #2+ after Pet and Beckon]
- You pet the Amalgamate. It starts to generate a Stage I Happiness Froth. [Pet after Play and Pet and Beckon]
- Amalgamate's convulsions intensify. [After Pet and Play and Pet and Beckon]
- You pet decisively. The Amalgamate seems to be satisfied by all this. [Pet #2+ after Play and Pet and Beckon]
- You threw the stick and the dog ran to get it. You played fetch for a while. [Using Stick]
- Monster has low HP. [Low HP; unused]
- Endogeny is contented. [Spare conditions met]
- You'd give it a tummy rub, but it's not clear where its tummy begins or ends. [Pet]
In Deltarune, a gravestone implied to belong to that universe's version of Endogeny lists its name as "Muttler". It is unclear whether this is its name in the Undertale universe as well.
In Chapter 3 of Deltarune, a silhouette similar to Endogeny appears in Ralsei's explanation of the Dark World, using the face of FRIEND.
- Endogeny's Check text is likely a reference to the "ABOUT THIS GAME" section on Undertale's Steam page, which states, "If you play this game, can you count the dogs for me? I'm not very good at it."
- The sound that plays in Endogeny's battle is named
mus_disturbing. It also plays in the shower curtain man's room. The sound effect audibly resembles or may be a distortion of washing windows that sounds like dog noises.
- ↑
You pet the Amalgamate. It convulses rapidly... Then calms down.
— Battle narration