The Hero of Kvatch is mentioned once or twice in Skyrim, I think, and it's implied that he has since fulled transformed into Sheogorath or something.
Contents MorrowindIn Elder Scrolls III:Morrowind, Barbas had a non-speaking role. This was in one of his few non-dog forms as he was a scamp at the time. In Ghorak Manor a scamp called 'Creeper' can be seen negotiating with some orcs.
He has a smaller gold pool than most merchants but he will not adjust prices to his advantage, selling items at market price, making him the best merchant in the game but with his limited money pool only allowing for a few items to sell at a time. Most player found Creeper to be the ideal merchant for selling off rare items while keeping common ones to more traditional merchants. As would be revealed in Oblivion, Creeper was in-fact Barbus. As Barbas usually tries to counter-act his master's more predatory practices, Barbas was likely doing this out of a simple charity to give the locals a fairer deal - as a Daedra, Barbas has no real use for gold anyway.OblivionIn Elder Scrolls IV: Oblivion, Barbas is encounter on Clavicus Vile's Daedric quest. Clavicus Vile was egged on into infusing a sword called Umbra with a sizable portion of his Daedric essence by a witch, (the witch is implied to be the rival Daedric Prince, in disguise). Dark souls 3 walkthrough. The enchantment on the sword stole the souls of all those it touches, while this takes the form of soul-trapping those it kills in soul-gems to be used for enchantments later, it affects more than just the blade, and even holding slowly wares away the users soul, eventually turning it's wielders into possessed hosts for the sword itself to kill. The sword and a previous Umbra were seen in Morrowind by a male Orc, but in Oblivion passed on to female wood-elf called Lenwin, though when met she is simply calling herself 'Umbra'.Clavicus has come to regret ever letting the witch invest his power in the blade and wants Umbra.
Upon making offerings at Clavicus Vile's shrine he tells the Hero of Kvatch to retrieve Umbra for him and he will hand over his boon. Barbas appears as soon as the, leaves to track down Umbra. Barbas warns that Clavicus's deals may seem tempting, but they are never worth it. He warns not to go after the sword. If the Hero of Kvatch investigates they will find out about Lenwin's possession and she is now a hardened murder, isolated in some ruins.
It seems Clavicus has two main goals for Umbra, the first is to gain back a sizable level of power used to create the sword from having it in his hands, the other is to have the current Umbra dead, so she does not complete her rampage later by slaughtering her former village and then moving on to Clavicus Vile's Shrine just beyond it. Umbra is a level 20 opponent regardless of level, so engaging her before that is extremely challenging. Barbas warns against it, telling the Hero to just turn around and tell Clavicus the deal is off, and that he will smooth out the issues with Clavicus.
Even if Umbra is killed, Barbas tells the Hero of Kvatch to keep it, that the sword will be better than any boon Clavicus will give.