The Fat Consul is the leader of the Roman troops stationed at Fort Sinister, seen in How to Speak Dragonese.
At some point, the Fat Consul was assigned to a Roman outpost called Fort Sinister in the Barbaric Archipelago, presumably to capture and ship dragons back "to the restaurants and shoemakers in Rome." He has at least one large Roman Ship to sail about, capturing dragons, though he is unable to actually partake in the process himself. He appoints Alvin, known as the Thin Prefect, as a second-in-command, or perhaps important advisor. Together they come up with a "Fiendishly Clever Plan" to acquire dragons: kidnap the heir to the Bog-Burglar Tribe disguised as Hairy Hooligans, and kidnap the heir to the Hooligans disguised as Bog-Burglars, causing a feud between the tribes. While they fight, the Romans can steal all the dragons from the Inner Isles.
The Romans succeed in capturing both heirs, along with Fishlegs. When Hiccup and Fishlegs are presented to the Fat Consul and the Thin Prefect, the Thin Prefect immediately wants to kill them, especially Hiccup. The Fat Consul, having been told that Hiccup is a great warrior, spares his life temporarily, as he wishes to see the warrior fight in the arena on Saturn's Day Saturday. Hiccup embellishes by telling him Fishlegs goes Berserk. So Hiccup and Fishlegs are imprisoned with Camicazi until the gladiatorial event, much to the disappointment of the Prefect.
When Saturn's Day Saturday arrives, the amphitheater area is flooded and Hiccup, Camicazi, and Fishlegs float into the arena on The Valhalla Express, where they fight Sharkworms. However, with a plan concocted with Ziggerastica, Hiccup appears to fly from the water and pretends to the Norse God Thor. Stunned, the Fat Consul offers "Thor" the Ceremonial Shield of the Legion and promises to leave the Barbaric Archipelago. "Thor" also orders him to become a vegetarian.
As his name implies, he is so fat that a slave must support his stomach and help him move from place to place. Like most Romans portrayed in the Book series, he is clean shaven. He wears a leaf wreath around his head and a large toga.
- "One of these men was very, very fat. So fat that parts of his stomach were dripping over the edge of his couch and were being held up by a small slave."
- ―Book 3
His overweight physique may contribute to health problems, such as having to "stop every couple of steps to catch his breath."
Later in "How to Speak Dragonese", the Fat Consul is also afflicted with eczema on his body. Though not implicitly stated, it is implied that his skin issues are caused by bites from nanodragons as retaliation for eating them.
The Fat Consul eats constantly, inducing vomiting to make space for more food. He favors exotic gourmet food, including but not limited to: baby Puff Nadders, dragon tongues, pickled Slitherhawks, shark's eyeballs, piccalilli penguins, live frogs, Monstrous Nightmare dessert, and sticky toffee Nadders.