That's one of the reasons we love him. Rogues are simultaneously loveable and backstabbing. He's the Han Solo of this mythology almost.
I thought that was Cyrus.
Yeah, Cyrus is Han Solo. Vivec is some god who pokes things with his Muatra and talks about stuff.
Vivec and Cyrus are the same archetype, at least I presume (and by this I don't mean to say they are exactly the same). They are both the Rogue, and I always assumed that is why Vivec is so fascinated with him at their http://www.imperial-library.info/content/lord-vivecs-sword-meeting-cyrus-restless. Here are some of the more essential bits:
And then Vivec spoke, and the winds of the beach died down when he did for he was the Lord of the Middle Air and they were indentured to him. He said to Cyrus, "Oh, I know you, raga. I know that you forced an armistice with the Cyrodiil, which I have done, though by other designs. I know also that even after speaking well and rendering your people free again, you remained a thief at heart in the days after; these days, in fact, which I have also done and still do, again in my own way."
And here the god of the East smiled a bit too lovingly. "And let it be said here that you have no idea how much I absolutely adore thieves."
...
"I know how you die," he said, "and the trouble your soul will have reaching the far shores of your taken stars because of things you did to the discredit of the Hist, and how their long roots run even into the void tendril-feeling for your final entrance. I know how you think now, at this moment, that there are no paths except for the drowned lamp, or the wrongheaded romance of saberplay in a landscape of long regret, taking whosoever will ride with you through the still-sought salvation spread across each water lash, wandering your heart to find some purchase beyond the admonishment of the moons; flagellant without end."
Vivec’s eyes went to the Glass Opal cradled in the pirate’s arm and frowned. He looked at Cyrus, dourly, saying, "I know all of this about you, Sura, and more, and it grants us a kinship despite your crime against me, and so it pains me yet that I think you really know nothing of me and my mastery..."
...
"Death despite kinship has ever been our way," he said, "I know too how it feels to murder the husband of my sister."