The development of the hydrogen (H) economy requires metals able to perform adequately in contact with H. The H uptake in a metal lattice, where it can interact with available defects, can lead to a sudden and complete loss of ductility, known as hydrogen embrittlement, which is among the most complex and least understood decay and damage phenomena. However, understanding how crack initiation and growth can be prevented is key towards an improvement of fracture resistance. The low H diffusion of the face centered cubic structure was longtime seen as the holy grail to prevent H-related failure. Nevertheless, due to its high H solubility and possible transformation to α’-martensite, H assisted cracking is still observed. Generally, multiphase steels including austenitic phases are considered among the most promising grades, where an increased ductility is obtained by the transformation-induced plasticity effect. However, the H trapping ability of retained austenite is still unclear. Joint work demonstrated that simultaneous H charging with mechanical loading allows retained austenite to trap H deeply. Either the mechanical loading itself makes existing defects available for trapping, or the combined effect of H charging and mechanical loading leads to an increased defect density. We aim to comprehend the H/defect interaction and its effect on the embrittlement from a combined experimental and numerical fundamental approach by making use of a specifically designed model alloy.