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We use a sample of 54 Compact Symmetric Objects (CSOs) to confirm that thereare two unrelated CSO classes: an edge-dimmed, low-luminosity class (CSO~1),and an edge-brightened, high-luminosity class (CSO~2). Using blind tests, weshow that CSO~2s consist of three sub-classes: CSO 2.0, having prominenthot-spots at the leading edges of narrow jets and/or narrow lobes; CSO~2.2,without prominent hot-spots, and with broad jets and/or lobes; and CSO~2.1,which exhibit mixed properties. Most CSO 2s do not evolve into largerjetted-AGN, but spend their whole life-cycle as CSOs of size $\lesssim$500 pcand age $\lesssim$5000 yr. The minimum energies needed to produce the radioluminosity and structure in CSO~2s range from $\sim~10^{-4}\,M_\odot{c}^2$ to$\sim7\,M_\odot{c}^2$. We show that the transient nature of most CSO~2s, andtheir birthrate, can be explained through ignition in the tidal disruptionevents of giant stars. We also consider possibilities of tapping the spinenergy of the supermassive black hole, and tapping the energy of the accretiondisk. Our results demonstrate that CSOs constitute a large family of AGN inwhich we have thus far studied only the brightest. More comprehensive CSOstudies, with higher sensitivity, resolution, and dynamic range, willrevolutionize our understanding of AGN and the central engines that power them.

Compact Symmetric Objects -- III Evolution of the High-Luminosity Branch and a Possible Connection with Tidal Disruption Events