The evolution of bright active galactic nuclei (quasars) and their massive host galaxies is expected to be strongly linked together, not only because both the star-formation and growth of the supermassive black-hole depends on the supply of gas, but also because the release and propagation of radiative and kinetic energy from the accretion disc to the galaxy interstellar medium. However, studying the gas around quasars in the distant Universe is difficult, owing to the bright glow of the nucleus, together with a loss of sensitivity and spatial resolution. Pasquier Noterdaeme has recently proposed to use a recently discovered population of proximate molecular absorbers (i.e. at the quasar redshift) to bring fresh new clues on the complex issue of AGN feedback. The project makes use of multi-wavelength spectroscopy both in absorption and emission, and benefits from wide observational expertise of Chilean astronomers.