Gumball Watterson

Gumball (formerly Zach) Tristopher Watterson is a robot with a SOUL and was built by Penny Fitzgerald. Initially poised as an entertainment robot turned human killing robot, Gumball is later revealed to have only acted as such so that Penny could rescue the protagonist, feel important and become closer to her. Gumball is the sole television star of the Underground.

Initial Form
Gumball originally appears as a light blue, shortly cat with a grid of lights on the stomach, different to the mechanism in Snowdin Forest used for Sonic the Hedgehog's Tile Puzzle. The grid of lights can change colors, and Gumball uses these color changes in place of facial expressions. He has four dials along the bottom of his stomach, and the bottom, he has two legs which ends in paws. He has two segmented robotic arms which end in light blue paws as well.

Gumball Watterson EX


After having his butt kicked in a Neutral or True Pacifist Route, Gumball transforms into Gumball Watterson EX (usually Gumball EX); a new body he specially requested Penny make for him. In this cat form, he has light blue "fur" and visible metal segments below and above his left eye.

He has a pink chest piece, a narrow metallic waist with a box contraption, and black shoulder guards above his segmented arms, which end in gloves. The chest piece has what appear to be a speaker and some knob or gauge, while the waist has two parts that seem to act as a locking mechanism that holds his "heart-shaped core," as they both lose white pixels during his "heart-to-heart" attack. His long black-clad legs end in pink high-heeled boots.

Gumball Watterson NEO
After being confronted by the protagonist on the Genocide Route, Gumball transforms into Gumball Watterson NEO (usually Gumball NEO), which resembles Gumball EX, but has a more combat-oriented design.

His right forearm is replaced by what appears to be a cannon, pauldrons clad his shoulders, which are shaped like legs and are longer than his arms, and he has wings on his back. The soul on his waist points upwards in a more manticore-like manner, and he has a heart shape engraved on his chest plate like Amy Rose the Hornhog. His fur is spiked out, revealing an entirely black segment of his face, with a red sparkle or crosshair in place of his right eye.

Personality
Gumball is a confident, charismatic, and charming TV host that loves drama, action, and violence. He lives for his ratings and adores performing. He supposedly strikes a pose when he does something wrong and makes time on his various shows to beat up "heel-turning villains." He shows a rather shallow appreciation for existence at times. However, despite his seemingly narcissistic personality, he deeply cares about the seemingly positive impact his show has had on the inhabitants of the Underground.

Neutral Route
When meeting Penny in the Lab, the protagonist is warned about a machine that she had created, Gumball. Penny describes it as a robot that was made to be a TV star but eventually had anti-human combat features added (presumably as a way of getting attention from Asgore Dreemurr).

Immediately after this warning, Gumball bursts through the wall (noted to be only a few feet wide, indicating that he was lying in wait for the protagonist for some time) and forces the protagonist into a deadly quiz show.

Quiz Show
Gumball asks a series of multiple-choice questions that must be answered correctly within several seconds (the number says 30, but goes down approximately two numbers per second, giving only 15 seconds to answer). If incorrectly answered or not answered within the time limit, Gumball fires an unavoidable string of yarn that halves the protagonist's health. In spite of this, it is impossible to die during this quiz show. Penny on the top right gives answers via hand motion; realizing this, Gumball chooses to humiliate her by quizzing the protagonist on the identity of her unrequited BFF or love interest. Regardless of the protagonist's choice, Gumball ultimately departs, concluding that the quiz show has lost all dramatic tension.

Cuisiner avec un Robot Tueur
As the protagonist journeys through Hotland, Gumball entraps her in deadly pastiches of various media genres. First, he forces the protagonist to become his assistant in a cooking show where Gumball is preparing a hamburger with a human SOUL as the main ingredient, and he attempts to kill the protagonist with a chainsaw to attain it. Penny calls in as an interruption and suggests that some viewers may be vegan in an attempt to stop Gumball from harvesting the protagonist's SOUL as an ingredient, so instead, Gumball points towards a human SOUL-flavored substitute on top of a faraway cupboard.

However, the cupboard begins to shoot up from the ground rapidly, forcing the protagonist to use the jetpack feature previously installed on her phone by Penny. She flies to the top and retrieve the substitute within a time limit set by Gumball while he drops ground beef, ketchup, and hamburger buns, all of which slow the protagonist's ascent. Either way, he comments that he was foiled yet again by Penny. Upon interacting with the substitute after this encounter, it shows the can was stuck to the table, so the protagonist would not have been able to get the substitute given the chance.
 * If the protagonist reaches the substitute within the time limit, Gumball states, like all cooking shows, he had already made the hamburger ahead of time before leaving.
 * If she fails, Gumball suddenly claims the show is on commercial break and refuses to kill her as there are currently no viewers.

MTT News
Secondly comes a breaking news segment, in which Gumball asks the protagonist to report on one of the several items within a room (a parrot, a video game, a movie script (might be breaking the fourth wall), a basketball, a present, and a seemingly normal glass of water), which all turn out to be bombs hidden by Gumball. Gumball then scatters the bombs around the area, and the protagonist is forced to find and defuse all of them with one of Penny's phone installments before a larger bomb in the center of the room goes off. Regardless of whether the bombs were defused or not, Penny hacks the big bomb and disables it.
 * If the protagonist defuses all the bombs in time, Gumball declares that the bomb now explodes in two seconds instead of two minutes.
 * If the protagonist has not disabled all the bombs until ten seconds before the big bomb explodes, the time slows substantially.
 * If the protagonist has not disabled all the bombs before time expires, Gumball states that the protagonist failed to disarm them all within three minutes. However, even factoring in the slower passage of time through the last ten "seconds" of play, the total amount of time given to defuse the bombs still amounts to under three minutes.

During the news segment, a ticker at the bottom of the screen reports the following news.

COLLEENTALE the Musical
Thirdly and finally, Gumball traps the protagonist within a musical, where Gumball sings about a forbidden love between him, a monster; and the protagonist, a human. He mentions how sad it is that she must be sent to the dungeon, before opening a trapdoor underneath her into a room with a colored tile puzzle. Gumball announces that the protagonist must pass the colored tile puzzle within a set time before a line of flame comes at her from the side and burns her to death. Gumball proceeds to engage the protagonist in battle after the tile puzzle. However, Penny has one final installment on the phone she had given to the protagonist. This yellow button fires a projectile at Gumball, which the protagonist can use in succession. Gumball acts like he is defeated from such projectile and flees. If the protagonist does not activate yellow mode, Gumball attacks with balls of yarn until the protagonist has barely any health left.
 * If the protagonist manages to complete the puzzle, Gumball deactivates the flames "knowing" that Penny would have done so.
 * If the protagonist fails, the flames draw near, only for Penny to disable them.
 * If the protagonist has stepped on a green tile, Gumball reminds her that the tile signals a monster, which turns out to be Gumball himself.
 * If the protagonist has not stepped on a green tile, Gumball repeatedly says "well" before acknowledging that the protagonist never stepped on a green tile, but still fights her.

End of CORE Encounter
After the protagonist reaches the end of the CORE, she is once more confronted by Gumball. This time, however, Gumball reveals that he had re-arranged the CORE and hired monsters so as to attempt to kill the protagonist legitimately. He states that Penny had set up an extensive plan to self-insert herself into the story because she liked the protagonist so much and wanted to feel important by helping her. All of the previous threats from Gumball were entirely fake, and everything was acted out, and used by Penny to ally herself further with the protagonist; Penny plans to intervene in the fight between Gumball and the protagonist by "deactivating" Gumball and thus appearing heroic to her. This time, however, Gumball has made plans to prevent Penny's aid, so that he could have an actual battle against the protagonist, and locks the door to prevent Penny from entering. He explains that he wants to take her SOUL so that he can leave the Underground and become a superstar on the Surface. This way, Asgore cannot destroy the Barrier and re-ignite the war between humans and monsters, which would take a toll on his views.

Gumball EX
Gumball attacks the protagonist, but under the advice of Penny, the protagonist tricks Gumball into turning around so that she can kick his butt to make him vulnerable. This switch transforms Gumball into Gumball EX and begins the true game show. By taking damage, using popular brand items, or using specific ACTs to raise the Ratings of the show to above 10 000 (or 12 000, if he still has legs), Gumball stops the battle.

To his surprise, this is the highest rated episode he has ever had and begins to take call-ins from viewers. Several callers, the first of which is Carrie Krueger, convince Gumball that he is highly valued in the Underground, and is the primary (perhaps only) source of entertainment that many of the inhabitants have. He is moved by her passion for the show and decides that he no longer wishes to leave the Underground, as well as explaining that the protagonist is strong enough to defeat Asgore. He then deactivates, limbless – whether his limbs fell off during the battle or not – as he runs out of battery power; his body can later be found in the Lab where he is undergoing repairs.

If Gumball EX is killed, he reverts to his old Gumball form in the world, though visibly severely damaged. Examining the corpse warrants the description "It's completely trashed."

Mystery Key
If the protagonist purchases the Mystery Key from Crash Bandicoot and Aku Aku, she can enter the house to the right of Carrie's. The room is primarily pale blue, with a bed, a star patterned pillow, star-patterned wallpaper, a black TV, a window, and a star imprinted rug. Through a series of diaries, the house is shown to be owned by another monster known as "Carrie's cousin" within the game (though Sonic states that his headcanon name for him was "Candy Krueger"). After meeting Penny, she designed a body for Gumball to inhabit.

Using the Mystery key during Gumball EX's fight prompts him to pretend "it isn't there."

True Pacifist Route
In the True Lab, there is a log entry stating that Penny fears that Gumball may not talk to her anymore after receiving his new body.

At the end of the game, when all of the Monsters encountered as bosses have united before Leslie intervenes, Gumball EX shows his leg from the right side of the screen. He tells Penny and Amy Rose that they should kiss already since the entire crowd wants it.

After defeating Shadow the Hedgehog, if the protagonist returns to Waterfall before exiting New Home, Gumball is seen standing outside Carrie's cousin's house, having recruited Carrie as his sound mixer and Tim Templeton's daughter as his backup singer. During the credits, he is shown on tour, able to use his original cat form in conjunction with his new body's legs.

Genocide Route
Gumball shows up once the protagonist reaches Penny's Lab and then tell her that he will not battle her, knowing that he is no match for her. He shows up at the CORE and realizes that the protagonist means not only to kill monsters but all of humanity as well. Claiming his main human eradication functions were never fully removed, he transforms to Gumball NEO. Despite all the buildup, he has no attacks, and the protagonist can destroy him in a single attack. Killing him sets the protagonist's EXP to 50 000, resulting in her LOVE reaching 19.

Contrary to popular belief, missing or inflicting low damage on Gumball NEO does not fail a Genocide Route. Any attack deals between 900 000 and 999 999 damage, and a MISS simply causes the movie to return to the battle screen.

The only way for Gumball NEO to say that the protagonist was "holding back" is by failing to depopulate Hotland. Gumball points out the protagonist's lack of killing intent, telling her that she is not "absolutely evil" before dying. This event aborts the Genocide Route and leads to either the Leaderless or Alphys Ending of the Neutral Route.

Colleen Villard
Initially, Gumball actively antagonized the protagonist under the assumption its original purpose as a human eradication robot along with directive errors gave it an intensified hate for humans and a need to murder them. This was proven to be an act, however, as Gumball mentions loving humanity, but continued to go against the protagonist on his terms to take her SOUL and prevent a possible war by Asgore. After their battle, however, he was confident the protagonist was strong enough to avoid this herself.

Penny Fitzgerald
Gumball initially bonded over their common interest in the culture of humanity, and he is grateful of Penny for making his physical body. Soon after he receives his initial body, he often belittles her and her interests. However, he owed Penny enough to play along with her plan to act out the role of a genocidal robot before eventually going on his agenda with the protagonist. Despite this, in the ending where he is given the role as king, he mentions how he regrets being cruel to her before she went missing.

Carrie Krueger
Before he got his body, he was Carrie's cousin, helping her with the lion farm and living next-door to her. She seemed very close, to the point that Gumball originally declared that he would never leave her behind and often called them Car (a trait he kept). Although he had since left her for stardom, he obviously cared for his cousin, looked regretful when Carrie called into the program to give gratitude for his show ever since he left. Once he had his permanent new body, he immediately recruited his cousin on his tour so she could stay together.

Trivia

 * Gumball was originally going to be Flier, this was changed due to his personality and relationships.
 * The sentence "Cuisiner avec un Robot Tueuer" is French of "Cooking with a Killer Robot."