Cerberus

Cerberus is a demon in the series.

History
Cerberus, in Greek myth, is a monster that guards the gates of the underworld, the realm of Hades and the dead. It is generally depicted as a vicious, gargantuan dog with three heads, although accounts may vary. Cerberus is in fact the Latin transliteration of the Greek name Kerberos. The dominance of Latin throughout the modern Western world was for many centuries precipitated by functionaries of the Roman Catholic Church. However within contemporary non-denominational academic discourse, the use of Latin for non-Roman words is in sharp decline.

Appearances

 * Digital Devil Story: Megami Tensei: Nakajima's demon familiar
 * Digital Devil Story 2: Warrior of the Demon City: Nakajima's demon familiar
 * Megami Tensei (Telenet)
 * Megami Tensei: Beast Race
 * Megami Tensei II: Beast Race
 * Kyūyaku Megami Tensei: Beast Race
 * Shin Megami Tensei: Beast Race
 * Shin Megami Tensei II: Beast Race
 * Shin Megami Tensei: if... / Hazama's Chapter: Beast Race
 * Shin Megami Tensei: 20XX / Devil's Colosseum: Beast Race
 * Shin Megami Tensei NINE: Beast Race
 * Shin Megami Tensei III: Nocturne: Beast Race
 * Shin Megami Tensei IMAGINE: Beast Race
 * Shin Megami Tensei: Strange Journey: Beast Race
 * Shin Megami Tensei IV: Beast Race
 * Shin Megami Tensei Gaiten - Hato no Senki
 * Last Bible as Cerbero in Revelations: The Demon Slayer
 * Last Bible II
 * Last Bible III
 * Majin Tensei: Beast Race
 * Majin Tensei II: Spiral Nemesis: Beast Race
 * Shin Megami Tensei: Devil Summoner: Beast Race
 * Devil Summoner: Soul Hackers: Beast Race
 * Devil Summoner: Raidou Kuzunoha vs. The Soulless Army: Pyro Order
 * Devil Summoner 2: Raidou Kuzunoha vs. King Abaddon: Pyro Order
 * Giten Megami Tensei: Tokyo Mokushiroku: Beast Race
 * Megami Ibunroku Persona: Fortune Arcana
 * Persona 2: Innocent Sin: Fortune Arcana
 * Persona 2: Eternal Punishment: Fortune Arcana
 * Persona 3 / FES / Portable: Strength Arcana
 * Persona 4 / Golden: Hierophant Arcana
 * Persona 4 Arena Ultimax
 * Persona Q: Shadow of the Labyrinth: Strength Arcana
 * Devil Children Black Book & Red Book / (PS)
 * Devil Children White Book
 * DemiKids Light / Dark Version
 * Devil Children Fire/Ice Book
 * Shin Megami Tensei Trading Card: Card Summoner: Beast Race
 * Digital Devil Saga: Avatar Tuner: Atma Avatar, Asura Race
 * Devil Survivor / Overclocked: Beast Race
 * Devil Survivor 2: Beast Race
 * Devil Survivor 2 The Animation
 * Tokyo Revelation

Megami Tensei (Telenet)
Cerberus is first seen when Nakajima enters Yesod. After being attacked by Loki, Cerberus decides to join Nakajima and can be summoned using the COMP.

Megami Tensei
Cerberus is encountered like any other demon near the end of the Tower of Daedalus within a corridor on the way to Valhalla. He is also featured on the game's startup screen and graphics, and appears in stills from the Digital Devil Story: Megami Tensei OVA printed within the game manual. He is unusually strong for a demon available so early in the game, with extremely high VIT and access to Recarm long before these things are available in any other way.

Megami Tensei II
Cerberus may be encountered and welcomed into the player's party via an optional side-quest which entails gaining access to the Intelligence Building by which the player's party is able to re-enter the Devil Busters video game.

Shin Megami Tensei
After having his mother killed and eaten by a demon, the protagonist can choose to add his dog, Pascal, into his party. In normal circumstances, Pascal serves as a low level ally. However, when fused with a demon in the Cathedral of Shadows, he transforms into the high level demon Cerberus. Because of Pascal's former loyalty towards his master passes on to him through fusion, Cerberus can be used even when his level far surpasses that of the Hero—something that is generally impossible. He aids him in only one boss battle however, disappearing through a Terminal after that boss fight.

Much later in the game, Cerberus stands on the bridge that leads to Tokyo Destinyland in a berserk state that can only be reversed if the protagonist possess the valuable "Golden Apple". Because of the power of this item to stabilize violent demons, Cerberus comes back to his senses and recognizes the Hero, thus choosing to share his fate by joining his party.

Shin Megami Tensei II
Cerberus first joins Aleph on the first quest Madam gives him: find and bring back Hanada. After this quest, he leaves the party. Later, when Valhalla is swallowed by Abaddon, he will be found at the former entrance to the city from the underground passageway. He joins Aleph's party shortly after meeting him for the second time.

It is revealed in extra visionary scenes in the GBA and iOS versions that he is the same Cerberus from Shin Megami Tensei, and maintains Pascal's memories and consciousness.

Shin Megami Tensei: if...
After defeating the boss of the World of Gluttony, a sidequest to recruit Cerberus becomes avaiable. If the player returns to Karukozaka High School, a broken CD can be found on the ground. The CD can then be taken to Katsuhiko Sato, the president of the school's computer club who will attempt to fix it, releasing the Cerberus that was stored inside. Katsuhiko then runs away from the demon and asks the protagonist to help. Cerberus, angry at being trapped inside the CD, demands that the protagonist let him pass. If the player refuses, Cerberus will start a fight right there. If the player complies, Cerberus will go but can be found in one of the rooms and challenged anytime. After being defeated, he'll recognize the strength of the protagonist and join the party despite the massive difference of levels.

Shin Megami Tensei: 20XX
Cerberus is an optional boss faced after completing Chernobog's challenge. Madam will call the protagonist and Ain to bring back her pet who has ran away. After being found, Cerberus appears to be brainwashed and attacks the party. Defeating it makes him summonable through fusion.

Shin Megami Tensei III: Nocturne
Cerberus first appears at the Burial Chamber in the Amala Labyrinth's First Kalpa, where it will challenge you to prove your worth as a demon by quickly vanquishing once more those that you have killed in the Vortex World using the Black Visor. After meeting all the requirements and starting a new cycle, meeting with Cerberus again in the same location will have him take you to his master's resting place instead at the Tomb of Yomi in the hidden 666th floor, where you will receive an extra Press Turn.

Cerberus can also be encountered and recruited inside the Diet Building.

Shin Megami Tensei IMAGINE
Cerberus is among the first demons to contract with the player as an injured demon that requests Snakeman to allow it to assist the player. This Cerberus is the former demon partner of DB Kuroe, the player's mentor from the tutorial and during the story he'll need to be returned to Snakeman. Once reaching level 30, a player regains the Cerberus as a stronger variation. Cerberus can be encountered within the gold level instance of Suginami Tunnels and appears regularly as a boss within the main storyline and as the final boss of the Suginami Tunnels Unknown plate boss rush. In the later acts, Cerberus is an intermediary for the leader of Protopia, Madam Justice, in giving story missions until a player has fully committed to the neutral route of the final acts. Within the neutral route, he is the boss players must defeat to gain access to the Ring of Human Being necessary to access the fight with Seth in Act 20.

Cerberus is the tutorial mountable demon and among the regular mounts within the game. Variations using the three-headed model from Digital Devil Saga can be acquired through events, special fusions, or a plug-in variant acquired through Shinjuku's Gomory called Asura Cerberus that learns the special skills Phlegethon and Pyriphlegethon.

Shin Megami Tensei IV
''Cerberus is fought in the Challenge Quest. Banquet of Flames. The quest involves an enraged Cerberus on a rampage around Tokyo, provoking local hunters to set a quest out for his defeat. After multiple encounters, Cerberus eventually calms down and returns to his realm.''

Devil Summoner: Soul Hackers
Cerberus possesses the Loyalty Slash technique, and until the 3DS remake this was his signature move.

In the 3DS remake, a variant Cerberus can be purchased from Nemechi (dango form), and costs 300 D-Souls. His artwork is based on his traditional design from the first Shin Megami Tensei. This version loses his vulnerability to ice magic and is better suited at casting spells, but does not have Loyalty Slash.

Persona 3
Cerberus appears as Koromaru's initial Persona. It is a fire and darkness elemental Persona and differs from the usual appearance as a black three-headed hound resembling a Doberman. The original Cerberus can also be accessed and used by the Protagonist by using a cheat device.

The Answer
When fought as an opponent, Cerberus can use several unique skills outside of its normal moveset, which are as follows:
 * Ragnarok (when fighting ???)
 * Brave Blade (in Colosseo Purgatorio)
 * Ghastly Wail (in Colosseo Purgatorio)
 * Life Drain (in Colosseo Purgatorio)
 * Megidolaon (in Colosseo Purgatorio)

Persona Q: Shadow of the Labyrinth
After the two Heroes complete the request, The Power of the Wild Card, Margaret explains to everyone how their Personas can now evolve and attain new power. Koromaru and Shinjiro stick around after everyone else is dismissed, and ask if it is possible for them to keep their personas, rather than attaining new ones. Koromaru explains, through Aigis, that he awakened his persona when shadows attacked the shrine he used to protect with his owner, and he now uses it to protect his deceased owner's house; he says that he does not want his persona to change so that he can never forget his failure to protect his owner. Margaret tells them that it should be possible for their personas to remain the same if they focus on keeping things the same when they start to attain new power.

Devil Children Black/Red Book
Cerberus appears in Devil Children Black Book as Cool, the demon companion to Setsuna Kai. Cool appears when Setsuna uses a Devil Riser to attempt to save his brother from Jack Frost.

DemiKids Light/Dark Version
Known as Nex, he has the power Odds Breaker, which lets him go for the win when the chips are down. Nex is obtained by beating Setsuna Kai in battlenet.

Digital Devil Saga: Avatar Tuner
Cerberus is the Atma Avatar of Lupa, the leader of the Wolves. He serves as the boss fight in the Samsara Waterways. In this title, Cerberus appears as a three-headed, eyeless beast.

The battle will begin as soon as the party reaches the light at the top of the ramp, across from the Large Karma Terminal that is designated Samsara Tunnels 3. Unlike most bosses so far, Cerberus does not have an actual weakness and resists everything aside from Ice and Physical attacks. Cerberus also has the High Counter and Counterstrike skills, which makes Physical attacks without retaliation difficult.

Cerberus has three heads, each of which fulfill a different role. Cerberus (R) uses buff and debuff spells along with Ice Repel. Cerberus (L) acts as a healer, but will focus on healing the center head. Finally, Cerberus (C) is the main attacking head. Each head grants Cerberus one press turn, so destroying a head will reduce the number of turns Cerberus can take.

The Animation
Cerberus serves as Yamato's main demon. Its status serves as a nod to a scene early in the game where Yamato uses it to dispatch some demons before showing the JP's underground trains to the party. He summoned it at the young age of 5, and it has accompanied him ever since. To date, Yamato has used Cerberus in fending off Phecda and Megrez.

Tokyo Revelation
Cerberus is summoned by Gagyson in order to kill Kojiro, who poses a threat to Gagyson's plans. Although he succeeds in killing Kojiro's dog Patra, he is stopped from finishing Kojiro thanks to a monk. The monk then defeats Cerberus and gives him an ultimatum: protect Kojiro or die. Choosing the former, he betrays Gagyson and takes the form of Patra while guarding him. After Ose is summoned he becomes the steed of Kojiro after the human incarnates into his true form, Masakado.

Trivia

 * Cerberus is one of the earliest demon allies to appear as part of the Megami Tensei franchise. His roots put him as far back as the very first Digital Devil Story: Megami Tensei publications.
 * Cerberus is one of the most frequently appearing demons in the series besides Jack Frost.