Robo (ロボ "Robo"?) is a robot originally created to assist humans at the Proto Dome in Chrono Trigger. His real name is Prometheus (プロメテス "Purometesu"?) while his serial number is R-66Y. He uses his robotic arm as a weapon and although Spekkio cannot grant him the power to use magic (Spekkio being unable to properly read his character), Robo can use laser attacks that are similar to Shadow magic and bomb attacks that are similar to Fire magic. He also sports several healing techs. Along with his sturdy physique and high physical damage capabilities, he is the most versatile character in Chrono Trigger.
Robo is shown to be very curious. Unable to comprehend human emotions at first, he analyzes and studies humans, taking them to be a very interesting, very puzzling race. He is friendly towards humans and refrains from the brutal force of killing and slaughtering the humans, unlike multiple robots in the Geno Dome.
Rotund and bulky, there is no doubt Robo packs a punch. Unlike the other R-Series robots similar in construction to him, which were recolored blue while Atropos XR was recolored pink, Robo is beige and brown. The color of his metal skin is presumably the result of the weather in 2300 AD, which appears to be severely polluted. The color may also be an attempt on the part of the game designers to highlight the dissonance between Robo and the other robots of this time era. His outer body equates to an exoskeleton of metal plates that splay or separate under duress or emotional excitement. Underneath, there is a soft layer of what appears to be black rubber
Robo is quite bipedal with two claw-like feet and two arms, one serving as a three-fingered hand and the other as a laser cannon or spring-loaded fist. Robo also has green eyes. Vents serve as the Robot's mouth and nostrils.
Robo is decidedly male. The other robots refer to him as such, and his romance with Atropos XR also alludes to the robot's gender. On his back, Robo wears what appears to be some sort kind of cooling gear, indicated by the smoke-spewing chimney that branches from it.
Having a curious and bright personality, he was rendered dormant by the Apocalypse in 1999 AD, but is found and repaired by Lucca in the year 2300 AD. Upon his reactivation, Robo has no memory of his prior mission and joins the party. Alongside Crono, Robo assists in shutting down the power in Derelict Factory, which controls the power of the nearby domes, and thus permits access to a Gate back to the Present. Within the Factory, Robo shares a not-so-warm reunion with the R-Series, his former comrades and mechanical brothers. Their combined effort damages Robo severely, but Crono and his friends succeed in preventing the R-Series Robots from causing permanent damage.
After the resurrection of Crono atop Death Peak, Robo learns that he originated from Geno Dome, a robot-producing Factory east of the Derelict Factory and isolated on an island. There, he is punished by his corrupted maker, Mother Brain, for having sympathy for humans, and he meets his long-lost companion robot Atropos XR. For the first time since Lucca reactivated him, he remembers his true function was to survey and service humans and prevents Mother Brain from spreading her poisonous tyranny to the other robots.
In the Middle Ages, Robo volunteers to spend four hundred years restoring Fiona's Forest. During this time, Robo ponders the existence of an Entity, a being who seemingly guided Crono and his friends through time the intended purpose of intervening in affairs the Entity grieves. He explains his theory to the party when reunited outside the Forest Shrine in 1000 AD.
After defeating Lavos, Crono's companions return to their own periods. Lucca and Robo share a touching farewell, the latter explaining that Lucca had shown him the meaning of human emotion. Thereafter, he procrastinates entering the Gate back to the Future, fearing that because he toyed with time, so to speak, he would cease to exist in his original time period. However, in the most common ending of Chrono Trigger, Robo still exists in the new timeline and as the Epoch is searching for Crono's mother, he and Atropos XR are seen overlooking a more beautiful landscape (as Lavos didn't destroy it in 1999 AD).
In Chrono Cross, Robo makes an appearance as the Prometheus Circuit terminated by FATE. However, after the ending of Chrono Cross, Chronopolis is most likely never built; and even if it were, Project Kid would not be started, so it is safe to assume that after you beat Chrono Cross, Robo is still alive. Masato Kato has officially gone on record as stating the circuit is Robo. "Anyway, if you have played Trigger, then Prometheus should be very familiar to you. I'm sure a lot of players would make a similar 'big fuss' over the death of such a much-loved friend..."
Robo is a very versatile character, able to take the most damage of any character while being a very strong physical attacker. He possesses a wide variety of single, dual, and triple techs, which inflict damage and heal other party members. His main downside is his slow speed, which can be remedied through Speed Tabs as well as low magic, which can also be similarly remedied with Magic Tabs.
Robo has no Magical element, so he has no weakness.