Density functional theory was employed to model adsorption mechanism and charge transfer interactions of fibrin protein molecules onto Au- and Ag-nanoparticles towards possible Au-nanoparticle + fibrin and Ag-nanoparticle + fibrin coronas. Negative adsorption energy values were noted for possible fibrin molecules adsorption onto Au- and Ag-nanoparticles. Mülliken charges and radius of gyration were further utilised to understand interactions of fibrin molecules with Au- and Ag-nanoparticles. Mülliken charges were analysed using population analysis approach to trace the charge distributions among fibrin molecules functional group atoms (H, N, and O) and surface atoms of Au- and Ag-nanoparticles. Mülliken charges analysis leads to either enhanced negative or positive charges on specified carbon (C1, C2, and C3) atoms after Au-nanoparticle + fibrin and/or Ag-nanoparticle + fibrin corona formations. Radius of gyration further suggest a tighter packing on the adsorption of fibrin molecules onto Au(38)/Ag(38), Au(55)/Ag(55) and Au(79)/Ag(79) nanoparticles in the following preference: Au(79)/Ag(79) > Au(55)/Ag(55) > Au(38)/Ag(38). Less tight packing of fibrin molecules onto Au(19)/Ag(19) nanoparticles was also noted. Tighter and less tight packing on Au-/Ag-nanoparticle + fibrin is associated with hard and soft corona formations respectively.