Cassia Orsellio is one of several Companions that can be romanced in Warhammer 40,000: Rogue Trader. She is a gifted Navigator and the esteemed heiress of House Orsellio with objectively one of the most engaging romance arcs in an RPG.
In Warhammer 40,000: Rogue Trader, Cassia can be recruited to your crew in Chapter One upon successful completion of the Secrets of the Navis Nobilite quest, which is an extension of the Looking for Trouble quest. Cassia can be persuaded—using any method—to join your Voidship, making her the first Companion to do so. But if you find yourself so inclined, you can also pursue Cassia romantically.