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A diverse range of peculiar properties across the domains of observation havemade OJ 287 one of the best-explored BL Lac objects on the issues ofrelativistic jets and accretion physics as well as the strong theory ofgravity. We here present a brief compilation of observational results from theliterature and inferences/insights from the extensive studies but focus on theinterpretation of its $\sim$ 12-yr QPOOs and high energy emission mechanisms.The QPOOs in one model are attributed to the disk-impact related to dynamics ofthe binary SMBHs while alternative models attribute it to the geometricaleffect related to the precession of a single jet or double jets. We discussimplications of the new spectral features reported during the 2015--2017multi-wavelength high activity of the source -- a break in the NIR-opticalspectrum and hardening of the MeV-GeV emission accompanied by a shift in thelocation of its peak, in the context of the two. The reported NIR-optical breaknicely fits the description of a standard accretion disk emission from an SMBHof mass $\sim~10^{10}~M_\odot$ while the time of its first appearance inend-May 2013 (MJD 56439) is in close coincidence with the time of impactpredicted by the disk-impact binary SMBH model. This spectral and temporalcoincidence with the model parameters of the disk-impact binary SMBH modelprovides independent evidence in favor of the model over the geometrical modelswhich argue a total central-engine mass in the range of $\rm 10^{7-9}~M_\odot$.On the other hand, the MeV-GeV spectral change is naturally reproduced by theinverse Compton scattering of photons from the broad-line region and isconsistent with the detection of broad emission lines during the previouscycles of quasi-periodic outbursts. Combining this with previous SED studiessuggests that in OJ 287, MeV-GeV emission results from external Comptonization.

A Multi-wavelength View of OJ 287 Activity in 2015-2017: Implications of Spectral Changes on Central-engine Models and MeV-GeV Emission Mechanism