How can one deal with the fact that my almost disabled brother watches many TV series, and the resulting fears about the reinforcement of negative ideas and the lack of condemnation of scenes of mixing and immodesty?

We ask Allah for your brother's healing. Watching TV series is forbidden if they contain unlawful elements. The guardian of a child must shield him from unlawful things, for accustoming him to them will affect him by making him not denounce them. This can be substituted with permissible cartoon scenes or recreational games suitable for his condition. We advise consulting psychological specialists and the counseling department.