A quantum particle strongly interacting with a nearby metallic particle is a fundamental system in nanoplasmonics. The dielectric function of the quantum system can manifest rich quantum nonlinear optics phenomena when the spatial dependence of the vectorial nature of the probing laser field and the dipole moment are considered. We find that the quantum system can exhibit giant gain and giant absorption when the dipole moment orientation and the direction, polarization, and relative phase of the probe field components are properly tuned, especially in the near-field regime. This can be explained as due to the strong interactions between the quantum system and the metallic particle in the near-field regime at surface plasmon resonance. Interestingly, these giant features can be suppressed by a large probe Rabi frequency. The study enables remarkable coherent control of optical properties in quantum nanoplasmonics, useful for enhancing absorption in solar cells and light amplification for lasing and sensing.