  Gluon dressing of the light quarks within hadrons is very strong and
extremely important in that it dynamically generates most of the observable
mass through the breaking of chiral symmetry. The quark and gluon parton
densities, $q(x)$ and $g(x)$, are necessarily interrelated since any gluon
emission and absorption process, especially dressing of a quark, contributes to
$g(x)$ and modifies $q(x)$. Guided by long-established results for the
parton-in-parton distributions from a strict 1-loop perturbative analysis of a
quark target, we extend the non-perturbative QCD approach based on the
Rainbow-Ladder truncation of the Dyson-Schwinger equations to describe the
interrelated valence $q_{\rm v}(x)$ and the dressing-gluon $g(x)$ for a hadron
at its intrinsic model scale. We employ the pion description from previous DSE
work that accounted for the gluon-in-quark effect and introduce a simple model
of the nucleon for exploratory purposes. We find typically \mbox{$\langle x
\rangle_g \sim 0.20$} for both pion and nucleon at the model scale, and the
valence quark helicity contributes 52\% of nucleon spin. We deduce both $q_{\rm
v}(x)$ and $g(x)$ from 30 calculated Mellin moments, and after adopting
existing data analysis results for $q_{\rm sea}(x)$, we find that NLO scale
evolution produces $g(x)$ in good agreement with existing data analysis results
for the pion at 1.3 GeV and the nucleon at 5 GeV$^2$. At the scale 2 GeV
typical of lattice-QCD calculations, we obtain \mbox{$\langle x \rangle_g^{\rm
N} = 0.42$} in good agreement with 0.38 from the average of recent lattice-QCD
calculations.
