Serum
In Undertale Yellow, a serum is an important plot element mentioned multiple times. Not all serums had their origins or effect explained in-game, creating confusion.
Chujin's Serum[edit | edit source]
After Chujin Ketsukane got fired from his engineering position in the Steamworks, he spent several years devising a plan for monsters to defeat humans in a war that he expected would break out after the monsters manage to break the barrier.[1] His plan was based on turning regular monsters into Boss Monsters, which, he assumed, would make monsterkind stand a threat to humankind. It involved a serum extracted from a fusion between a Boss Monster SOUL and a human SOUL.[2] His experiments were stopped by his death, and he asked his wife, Ceroba Ketsukane, to continue his research.[3]
During Chujin's experiments, a human with the blue SOUL (Integrity) fell into the Underground and attacked a monster that Chujin's daughter, Kanako, was with.[4] Chujin sent his creation, Axis, after the human, and Axis chased the human and killed them.[5] This allowed Chujin to retrieve a human SOUL to experiment with.
During Ceroba's experiments, due to the near impossibility of finding another, pure, human SOUL, she tried to remove corruption from an extract of the human's SOUL.[6] As instructed by Chujin, she tried not to use Kanako's SOUL during her experiments, but when Kanako saw Chujin's tapes she insisted that Ceroba test the extract on her. What Ceroba intended to do was inject the purified extract into Kanako's SOUL using one syringe, then extract the completed serum with another syringe. The test went awry when Kanako's SOUL received a visible crack after the injection, which made her fall down. Therefore, Chujin's Boss Monster serum was never created.
It is not stated what caused Kanako to fall down. It could be that Ceroba incorrectly purified the extract due to either not knowing how to or it being impossible to do so. It is also possible that Chujin's plan was flawed to begin with and even a pure human SOUL would not work.
Martlet's Serum[edit | edit source]
During the Neutral and Genocide Route, Martlet is stated to have carried a syringe with herself in case Clover starts a rampage.[7] Martlet throws the syringe away at the end of a Neutral Route, and injects herself with it at the end of a Genocide Route, turning into her final form. The syringe is also stated to contain a serum.[8]
This serum is confirmed to be determination that Martlet stole from the True Lab. This was before Alphys began injecting the fallen down, and it is likely that Martlet did not have many details on what it did.[9] Martlet is shown to enter the True Lab in a flashback during her boss battle, right after Chujin expresses concern for her joining the Royal Guard and warns her that humans are dangerous; this is where she got the determination. A large piece of evidence that this is determination is its effects. Injecting herself with the serum changed her form to make her strong enough to face against a powerful human, but when she is injured or after time, she melts similarly to Undyne. Martlet is stated to have fallen down at that point,[10] and Undyne's health had already dropped to 0 before she starts melting. Some smaller pieces of evidence are that Retribution contains a motif from Battle Against a True Hero and that Final Stand, a previous idea for her boss theme, contains the Determination motif.
Trivia[edit | edit source]
- Some fans believed Martlet's serum to contain an extract from the blue SOUL; whether the extract was Chujin's, or extracted from the blue SOUL after it was handed to Asgore, would be unknown. While deconfirmed, this was supported by some evidence:
- A drop of liquid is visible falling down from Martlet's arm after she injects herself with the serum, and the puddle it forms shortly after falling is blue in color.
- Martlet, as well as her battle interface, are themed blue during her battle.
References[edit | edit source]
- ↑ They believe once he gets seven SOULs and breaks the barrier...
...he'll easily be able to overthrow whatever awaits on the Surface.
A rather foolish outlook if you ask me.
Who knows how the humans have prepared for retaliation since then? - Ceroba in Steamworks commons on a Pacifist Route - ↑ As a nation, an army, we could finally possess enough power to take the Surface back!
My theory for this involves the fusion of a human SOUL and a Boss Monster SOUL.
From that, a serum would be extracted which could transform any average monster. - Chujin in his fourth tape found in the Ketsukane Mansion - ↑ My SOUL has deteriorated and I don't know how much longer I have.
However... I believe my theory holds stronger than it ever did.
This is a message to my dear Ceroba:
This research is up to you. No one else would listen. - Chujin in his fifth tape found in the Ketsukane Mansion - ↑ A few panicked townsfolk ran up to me saying that a human had entered the area.
This human... they attacked the monster Kanako was with. - Chujin in his second tape found in the Ketsukane Mansion - ↑ The human who almost hurt my child, I told Axis to track them down. [...] Axis soon contained the subject and... hid the evidence. [...] I now have a human SOUL in my possession. - Chujin in his secret videotape
- ↑ Kanako: "Using the leftover ex... extract from the human's SOUL...
I believe I have removed any corruption it held."
Ceroba: ...Negating the need for someone pure of heart. Yes. - Ceroba and Kanako during a Pacifist Route final battle cutscene - ↑ I had this backup plan in case you started a rampage but...
...you never did. - Martlet at the end of a Neutral Route - ↑ W-What's going on?
The s-serum, it...
N-No! I can handle it! - Martlet during the second phase of her final battle on the Genocide Route - ↑ Undertale Yellow 1st Anniversary Developer Livestream (Featuring Shayy) (Extra Life Charity!) - YouTube
- ↑ Fallen down. - Martlet's Check text during the second phase of her fight