I will highlight recent science results from Keck/KPIC (R~35000) K-band high-resolution spectroscopy. KPIC has detected 32 giant exoplanets and low-mass companions, including HR 8799 bcde, AF Lep b, and PDS 70 b. First, KPIC enables the first detection of atmospheric CO and water species in PDS 70b. PDS 70b atmosphere shows a stellar-like C/O ratio and metallicity consistent with its host star, in contrast with that of the gas-rich outer disk. This implies that the PDS 70 b accretions were dominated by dust and ice, or the disk became carbon-enriched after its formation. Next, our survey for young substellar companions (~10-30 MJup) along with PDS 70 b indicates that their metallicities and C/O ratios are broadly consistent with the solar compositions. Finally, we find a tentative spin trend versus mass that separates the imaged giant exoplanet and brown dwarf companion populations, with giant planets exhibiting faster spins than more massive brown dwarf companions, demonstrating that spins can be a powerful probe to differentiate the formation between giant planets and brown dwarf companions.