We investigated how coherent interfaces, between face centered cubic (fcc)/hexagonal close packed (hcp) systems, affect large strain deformation and fracture modes in hcp zircaloy aggregates with fcc hydrides. We derived 36 unique transformations related to coherent interfaces between fcc and hcp systems. We then used these orientation relations (ORs) with a dislocation-density crystalline plasticity formulation, a nonlinear finite-element, and a fracture approach that account for crack nucleation and propagation. We investigated how these ORs affect crack nucleation and propagation, dislocation density and inelastic slip evolution, stress accumulation, lattice rotation, and adiabatic heating. The predictions indicate that the physical representation of ORs affects local deformation and fracture behavior and are, therefore, essential for the accurate predictions of behavior at different physical scales in heterogeneous crystalline systems.