Vennet is a dragonmarked heir of House Lyrandar and the captain of the elemental galleon "Lightning on the Water", which primarily travels between Yrlag, Zarash'ak and Sharn.
He transported Geth, Etan Bayard and Natrac to Zarash'ak from Yrlag, and later turned on them when they met up with Tetkashtai. He is seemingly working with Dah'mir.