Abstract: A Factor VIII fusion protein or a Factor VIII fusion heterodimer comprising Factor VIII in which an amino acid sequence of a modulator is present in the B-domain, or an amino acid sequence of a modulator replaces some or all of the amino acid sequence of the B-domain is disclosed. Nucleic acids encoding the inventive fusion proteins and fusion heterodimers are also disclosed, as are methods for producing the fusion proteins and fusion heterodimers, pharmaceutical compositions, and methods of treating deficiencies in coagulation with the inventive fusion molecules.