Paper Mario: The Thousand-Year DoorEdit
Doopliss lives in Creepy Steeple, in possession of the Ruby Star, and often thinks of pranks to pull on the people of Twilight Town. One day, he cursed Twilight Town so that whenever the bell rang, someone in Twilight Town would turn into a pig. He was widely feared as a monster, although when Mario and his partners, Goombella, Koops, Flurrie, and Yoshi, arrived at Creepy Steeple, they found he did not look very intimidating. He was not very powerful either, and was easily defeated, despite turning into Shadow Mario and using all Mario's attacks.
Though his curse was broken, he stole Mario's name and body, leaving Mario as a shadow unable to use his name. He left with Mario's partners, who did not know who he really was, and went to Twilight Town. Discovering that Mario was famous, he decided he wanted to be Mario forever, and received a Mushroom from Mayor Dour of Twilight Town. He attacked Mario as he made his way to Twilight Town, and decided to let him guess his name. The letter "p" was missing from the text menu, and Mario was unable to guess his name, so Doopliss fought Mario. Neither could damage the other, so Mario ran.
Doopliss attacked Mario again as he made his way toward Creepy Steeple again with Vivian to find out from a bird what Doopliss's name was. Mario was again unable to guess his name so Doopliss entered battle, but Mario ran.
Mario soon found the missing letter in a chest in Creepy Steeple, as well as a parrot, whom Doopliss locked away because he knew his real name. He said Doopliss's name when Mario and Vivian were listening in on him in the shadows. They encountered Doopliss again at his usual spot in Twilight Trail, and Mario said his name was Doopliss. Doopliss lost his power and ran off toward Creepy Steeple. Mario and Vivian returned to Creepy Steeple and fought Doopliss again. This time Doopliss had Mario's partners with him, still thinking he was Mario and that Mario was Doopliss. Vivian realized who Mario was and initially did not fight alongside him (as he was an enemy of Grodus, whom she and her sisters worked for) but then decided to stay with him until the end. Mario and Vivian defeated Doopliss, returning him and Mario to their original forms and revealing to the other partners that Doopliss tricked them. Doopliss jumped out the window, leaving behind the Ruby Star, which Vivian gave to Mario.
When Beldam heard from one of Mario's partners that the sixth Crystal Star was in Poshley Heights, she sent Doopliss onto the Excess Express. disguised as Zip Toad, to blow up the train. Doopliss left a threatening note to Mario telling him to get off the train and abandon his search for the Crystal Star, or else a "sticky yummy doom" would await him. On the second day of the voyage, Doopliss stole shell earrings from the waitress, a gold ring from Toodles, and the briefcase of a Ratooey businessman, containing his Nitro Honey Syrup. Beldam's plan was for Doopliss to mix the seashells, gold, and Nitro Honey Syrup to cause a gooey explosion that would destroy the train. It is unknown how Doopliss intended to avoid the explosion himself. However, he was caught by Mario while hiding in his room, and Pennington realized he was a fake due to a discolored nostril hair. He made Doopliss hand over the stolen items, which Mario returned to their owners. The conductor intended to question him, but he revealed his true form and escaped into Riverside Station.
It is unknown if he was connected to the Smorgs at all.
Beldam, Marilyn, and Doopliss got to Poshley Sanctum before Mario, with Doopliss breaking through a window. They took what appeared to be the Garnet Star from its pedestal, but was really a fake. Mario found the real Crystal Star, which even Pennington did not know the location of (but pretended otherwise).
After Mario returned from the X-Naut Fortress with all seven Crystal Stars, Doopliss appeared, disguised as Professor Frankly, saying he saw Grodus go through the Thousand-Year Door with Princess Peach. It was never suspected that he was really Doopliss; his tattle here is identical to that of the real Professor Frankly. In the Palace of Shadow, Mario encountered the Shadow Sirens, and Doopliss revealed that he was the Professor Frankly they were with when they opened the Thousand-Year Door. They fought Mario, but were defeated, knocking them out. They later returned when the Shadow Queen was awakened, and watched the battle between Mario and the Shadow Queen. When Mario defeated the evil demon of darkness, Beldam and Marilyn retreated into the shadows and Doopliss, who possessed no such power, ran off.
Afterward, Doopliss stopped being evil, and became an actor in Flurrie's play of their adventure, entitled Paper Mario. Doopliss portrayed Mario, and possibly other characters, using his transformation abilities.
In the first battle, Doopliss is referred to as ????? by the enemy select, as his name is unknown until the parrot says it. He has 40 HP, 4 ATK, and 0 DEF. He attacks by flying at Mario for 4 damage. Once he loses about half his HP, he will transform into Shadow Mario. He uses hammer and jump attacks, but still can do no more than 4 damage with each attack. He is easy to defeat, especially if Mario has Yoshi as his partner.
Doopliss will be fought at least twice more before Mario can guess his name, as the battle is initiated by guessing his name wrong. Both Mario and Doopliss are immune to damage. The battle cannot be won. The only way to end the battle is for Mario to run away. He will not lose any coins from this as he would from any other enemy (outside the Glitz Pit).
The second true battle with him, Doopliss is in the form of Mario for the entire time, and Mario is a shadow. Doopliss has the same stats and uses the same techniques. The only two differences are that Vivian is Mario's only partner, and Doopliss is using Mario's partners. Vivian's attacks do 3 damage (she cannot be upgraded to Level 2 before the battle, as Mario cannot return to Rogueport as a shadow), but burn whoever they hit, doing 1 extra damage per turn. Doopliss will have Goombella out at the start of the battle. He will only switch her out if she is defeated, in which case he will bring out Koops. If Koops is defeated, he will bring out Flurrie, and if she is defeated, he will bring out Yoshi, which will make the battle extremely difficult, so Mario should focus all attacks on Doopliss rather than Goombella. Vivian will not enter the battle until two turns have gone by. The battle will end once Doopliss is defeated.
The third battle with him, he fights alongside Beldam and Marilyn. The only stat that has changed is his attack, which is now 6. He can transform into Mario (performing a regular transformation this time) and also he can turn into Mario's partner and use his or her attacks as well. None of his attacks can do more than 6 damage, however, and he is the least dangerous of the three Shadow Sirens. Beldam can inflict negative status effects on Mario's team while using positive ones on her team, and Marilyn can charge her attack power high. Doopliss should be defeated last.
- Doopliss is similar to Rumpelstiltskin, the villain of a fairy tale named after him, as both can only be defeated if someone guesses their name.
- His name is a reference both to his species, Duplighosts, and to the word "duplicity", which means deceitfulness.