Fevre Dream by George R. R. Martin

Set against the backdrop of the Mississippi River in the mid-19th century, this gripping tale follows the journey of a steamboat captain, Abner Marsh, who partners with the enigmatic and wealthy Joshua York. As they navigate the river's treacherous waters, Marsh discovers York's dark secret: he is a vampire seeking to end the bloodthirsty ways of his kind. Together, they face a dangerous adversary who threatens to unleash chaos and destruction. The novel weaves themes of friendship, loyalty, and the struggle between good and evil, all while exploring the rich tapestry of life along the mighty river.