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Context: The accretion history of the Milky Way is still unknown, despite therecent discovery of stellar systems that stand out in terms of theirenergy-angular momentum space, such as Gaia-Enceladus-Sausage. In particular,it is still unclear how these groups are linked and to what extent they arewell-mixed.  Aims: We investigate the similarities and differences in the propertiesbetween the prograde and retrograde (counter-rotating) stars and set thoseresults in context by using the properties of Gaia-Enceladus-Sausage,Thamnos/Sequoia, and other suggested accreted populations.  Methods: We used the stellar metallicities of the major large spectroscopicsurveys (APOGEE, Gaia-ESO, GALAH, LAMOST, RAVE, SEGUE) in combination withastrometric and photometric data from Gaia's second data-release. Weinvestigated the presence of radial and vertical metallicity gradients as wellas the possible correlations between the azimuthal velocity, $v_\phi,$ andmetallicity, [M/H], as qualitative indicators of the presence of mixedpopulations.  Results: We find that a handful of super metal-rich stars exist on retrogradeorbits at various distances from the Galactic center and the Galactic plane. Wealso find that the counter-rotating stars appear to be a well-mixed population,exhibiting radial and vertical metallicity gradients on the order of $\sim$-0.04 dex/kpc and -0.06 dex/kpc, respectively, with little (if any) variationwhen different regions of the Galaxy are probed. The prograde stars show a$v_\phi$-[M/H] relation that flattens -- and, perhaps, even reverses as afunction of distance from the plane. Retrograde samples selected to roughlyprobe Thamnos and Gaia-Enceladus-Sausage appear to be different populations yetthey also appear to be quite linked, as they follow the same trend in terms ofthe eccentricity versus metallicity space.

The chemodynamics of prograde and retrograde Milky Way stars