Axion-like particles may play a key role in early universe cosmology. They are naturally equipped with the right properties to explain cosmic inflation, can dynamically explain the smallness of the electroweak scale, may be involved in the generation of the matter antimatter asymmetry and are promising dark matter candidates. In this talk I discuss a generic but previously overlooked particle particle production mechanism, resulting in the dual production of gauge fields and fermions induced by axion-like particles. I demonstrate how this crucially impacts all of the cosmological scenarios mentioned above and may be probed with upcoming gravitational wave detectors.