  Tomonaga-Luttinger liquid (TLL) behavior in one-dimensional systems has been
predicted and shown to occur at semiconductor-to-metal transitions within
two-dimensional materials. Reports of mirror twin boundaries (MTBs) hosting a
Fermi liquid or a TLL have suggested a dependence on the underlying substrate,
however, unveiling the physical details of electronic contributions from the
substrate require cross-correlative investigation. Here, we study TLL formation
in MTBs within defectively engineered WS$_2$ atop graphene, where band
structure and the atomic environment is visualized with nano angle-resolved
photoelectron spectroscopy, scanning tunneling microscopy and scanning
tunneling spectroscopy, and non-contact atomic force microscopy. Correlations
between the local density of states and electronic band dispersion elucidated
the electron transfer from graphene into a TLL hosted by MTB defects. We find
that MTB defects can be substantially charged at a local level, which drives a
band gap shift by $\sim$0.5 eV.
