Jaqon resembled a clean shaven satyr with red skin and green eyes. He also had pointed ears and small, curved horns like those of a pit fiend. He typically wore a weapon harness bearing a whip and rapier, and a backpack.
Jaqon was an archdevil, and possessed an outlook typical of that kind: the strong ruled and the weak obeyed. He was a skilled actor and diplomat when he needed to be. However, he also considered himself above the rulings and decrees of Asmodeus, and felt a sort of kinship with the archdevil Geryon and the rebellious pit fiends that dwelt on the edges of Cania.
Jaqon could fight with his bare hands, or with weapons such as a whip and rapier. Being an archdevil, he possessed a number of magical abilities. At will, he could use pyrotechnics, produce flame, wall of fire, ice storm, wall of force, charm monster, hold person, beguile, read magic, read languages, tongues, detect magic, see invisibility, polymorph self, invisibility, detect lie, locate object, obscure alignment, and misdirection. Once each day he could use meteor swarm and wall of thorns.
Jaqon was originally an archdevil of Asmodeus's court, serving the Lord of Nessus as herald and messenger. However, certain unpleasant activities of his led to his expulsion from the diabolical hierarchy and exile to Avernus. The activities that led to his exile included procuring substances from the Nine Hells at summoners' requests, for a fee; giving information to summoners to aid in the summoning of other powerful devils; and giving hints at the truenames and preferences of various she-devils to the archdevils who sought their hands. For that last crime, all of the consorts in Baator despised him.
To make his exile a punishment, Asmodeus forcibly changed Jaqon's truename to Dagon- an insult to both the archdevil and the demon prince of the same name. However, it was effective: anyone who tried to summon Jaqon would instead get the more powerful demon prince's aspect. It was an effective foil to an archdevil that was used to being summoned frequently.
Trapped in Avernus by Asmodeus' decree, Jaqon was forced to roam that layer. He often pretended to be an unlucky woodland creature who was searching for a way "home" to the Material Plane.
His immediate goals were to convince another creature, one that could leave Baator, to spread the word of his name-change and the means of summoning him again amongst summoners. To that end, he was polite and helpful.