Robin

Robin is an employee, presumably for the Bergmann Group or Walter Co. who was assigned to maintenance jobs in the tunnels and in various power and water treatment plants. Robin is partially responsible for Stalburg's crumbling infrastructure, but this is due to his incompetence rather than malice.

Biography
Robin was initially hired to help Erik maintain the Bergmann tunnels after the Bergmann Group's bankruptcy. To Erik's dismay, Robin was terrible at his job, and often caused more problems than he fixed, even going as far to hide valves to broken flood doors to cover-up his mistakes. Despite this, he and Erik managed to get along well enough, even eating green hallucinogenic mushrooms together.

Robin was briefly employed at the Stalburg Central Water Plant, where he apparently caused problems with the freshwater system, and likely caused the flocculation pool to malfunction. After this, it can be assumed he was relocated again to a coal-fired powerplant, where he took shifts with a co-worker, Ervin, and caused similar problems. Robin is often the one responsible for workplace injuries, too.

Robin is frequently mentioned in documents that can be seen in many parts of Stalburg, mostly maintenance logs and complaints about his idiocy.

Story
Robin is never met in person, and is only encountered by Mark in the Coal-Fired powerplant, where he is currently employed and still causing chaos. Mark makes contact with him over a handheld transceiver. Robin, initially confusing him for Ervin, recognizes Mark's voice, and tells him the situation regarding power-cuts all over the city. He then asks Mark to help him do maintenance on one of the generators in the powerplant. Mark synchronizes it, and activates it, but a mistake caused by Robin causes the generators to explode, and electrocutes Mark into unconsciousness.

Robin manages to wake Mark up through the walkie-talkie and tells him to get out of the powerplant, but finds himself trapped in a nearby control room, with smoke filling the room. Mark can choose to help him and ensure he survives the events of INFRA, his fate changing depending on the ending received (and if Rob was helped).

Rob Madsen
Robin is close friend to Rob, in the good ending, they'll found their own repair company, fittingly named Rob-In, Build and Repair.

Erik
Despite the initial rocky start, Robin and Erik were on friendly terms by the time the Bergmann tunnels became completely uninhabited. Erik left a note to Robin following his retirement, as well as maintenance instructions, promising to return to visit him sometime. Robin may of unintentionally sent Erik to the hospital through his failure to repair a generator, causing the ceiling to collapse, and confused Mark for Erik once.

Markku Siltanen
Robin is friendly towards Mark, and seems to share the same interest in keeping things maintained. If saved by Mark, Robin will express his gratitude and promise to repay the favor. He will also go on to tell a friend of his Rob, about Mark's good deeds.

Trivia

 * It's never explicitly explained how Robin knows Mark, although it's possible Robin is employed by National Consulting Group.
 * Robin is a descendant of the infamous "Sir Robert" mentioned in isle2 who blew up the Castle Stalburg storehouse.
 * Interestingly, Robin's "model" can be seen facedown in the floor in powerstation2 by noclipping behind a broken door.