Marcus Damon

History
Marcus is a fourteen year-old student and loves to fight. He lives with his mother and younger sister Kristy (Chika). Marcus meets and fights Agumon in the first episode of the series. When the fight ends in a draw Agumon agrees to become his partner. Soon afterwards he's recruited as a member of D.A.T.S. As Marcus's partner, Agumon idolizes him and refers to him as his "aniki" (兄貴, a Japanese colloquialism for "older brother," used in this case with the connotation of "boss" as seen in the Yakuza).

Marcus is one of the few humans able to fight Digimon by himself, though he still counts on Agumon's help to fight the stronger opponents. Even though other humans can evoke their Digisouls by themselves, Marcus must connect a punch on an enemy to do so, subsequently using it to Digivolve Agumon.

Heading to the digital world
Before leaving Earth to confront Mercurimon, Marcus gained an alternate motive for going to the Digital World: to find his father Spencer (Suguru) who he believes to still be alive and bring him back home. However, the only clue he has about his whereabouts was given by Mercurimon himself, who revealed to be a friend of Spencer and said he set off in search for Yggdrasil, the god of the Digital World in his effort to build a coexistence between humans and Digimon.

Marcus only learned anything else about Spencer when he and his friends reached ElDoradimon and learned that the people there has a debt of gratitude with him for helping the city years ago. They swore to protect the city from Kurata's army, but in the end little they could do to prevent ElDoradimon from being destroyed.

Another moment of despair occurred when Thomas, for personal reasons was forced to side with Kurata and he had to fight him. During the battle between ShineGreymon and MirageGaogamon, Marcus' anger triggered the dark digisoul inside himself dark- digivolving/mode changing his partner to a corrupt and rampaging version of ShineGreymon Burst Mode ( known as ShineGreymon Ruin Mode), after finally stopping him, he returned to a digi-egg state. But did not take long for Agumon to return to life and Marcus bring him properly to ShineGreymon Burst Mode this time to fight Belphemon.

After Belphemon's defeat the D.A.T.S. team face a threat even greater when Yggdrasil, the god of the Digital World, decides to wipe out the Human World to end the struggle between the worlds once and for all, with the help of the Royal Knights. Marcus confronts Yggdrasil himself, just to discover that he is in fact Spencer Damon, his long lost father. After being rescused by Sleipmon, Marcus intends to go back to the Digital World to confront his father.

After meeting up with Gotsumon again, Marcus and Agumon faced off against Craniummon once more, where the GeoGrey Sword actually broke. With help from the others, they were permitted to see Yggdrasil. Upon reaching Yggdrasil, Marcus fought his father, but couldn't land a hit. However, after hearing his father's disembodied voice, and with help from the Digimon, Marcus was able to connect a hit. BantyoLeomon appeared to help Marcus, only to reveal that he was in fact, the real Spencer. BantyoLeomon explained everything to Marcus, how he knew Spencer, how Yggdrasil took Spencer's body, etc. When Yggdrasil began attacking them, BantyoLeomon grabbed onto him and told Marcus to kill both of them. With severe hesitation, Marcus invoked his Digisoul and digivolved Agumon to ShineGreymon. He ordered ShineGreymon to unleash the attack that took them out. Just before the attack hits, BantyoLeomon and Spencer both thank Marcus. With Yggdrasil seemingly defeated, and the World Tree destroyed, everything seems like it's over. However, Yggdrasil's true form appears and Marcus and the others prepare for the final battle.

While Marcus and the others fought against Yggdrasil, Yggdrasil decides to remove their reason for fighting by destroying Earth. The battle later resumes on Earth, where even the remaining Royal Knights come to help them. When the Digimon are defeated, Marcus and the others use their Digi-Soul to try and stop the two worlds from colliding. When every Digimon around began helping, Yggdrasil began attacking them too. Marcus and the others stood up once more to fight. While the others worked on protecting them, Marcus and Agumon charged at Yggdrasil. Marcus' Digi-Soul soon gave a Agumon a new form, giving him bird-like wings and a bird-like tail (dubbed by the fan as Agumon Burst Mode). Together they defeated Yggdrasil once and for all. After discovering that the border had been fixed and reuniting with his family, Marcus discovered that Spencer's life had been restored by Yggdrasil. All was well, until the Digimon announced that they were returning to the Digital World. After realizing he couldn't give up Agumon, Marcus decided to join the Digimon and went to live in the Digital World with Agumon.

Five years later, Marcus and Agumon are seen intervening with a fight between a group of Goblimon and Shamanmon.

At some unspecified time, Marcus, Thomas, Yoshino, and the rest of the city's population were trapped in a deep sleep within cocoons created by the evil digimon Argomon, who also had covered the entire city in vines. Agumon, Gaomon, and Lalamon were the only ones who could face him and, with the help of the digimon-disguised-as-a-human named Rhythm, they were able to wound Argomon enough to where Marcus could free himself. Marcus punched the now Mega-leveled Argomon, summoned his digi-soul, and digivolved Agumon to ShineGreymon to do battle with Argomon. Marcus then summoned the GeoGrey Sword to help ShineGreymon, but it took the power of ShineGreymon Burst Mode to destroy Argomon. Marcus, along with the other digimon, said goodbye to Rhythm as she went back to the Digital World.

Agumon

 * See Agumon (Savers)

Trivia

 * According to the first episode, his birthday is the same day as day Digimon Savers started in Japan, April 2.
 * Marcus is the first human lead character of any Digimon series (anime as well as manga) that doesn't wear goggles. Marcus is also the first "good" human to hurt a digimon on a regular basis.
 * His name is probably also an intended pun as it could be read Daimon Dai while daimondai means "big problem", which would make sense given his love for fighting.
 * He appears in quests of the game Digimon World D.S.
 * In the Japanese version, when refering to himself, Masaru adds -sama onto his name, which in Japan, shows great arrogance.

Masaru Daimon Daimon Masaru