As far as the Roles and Responsibilities are concerned, who does what when Mental Health is involved? It's a big question to answer, and when answered correctly, could launch your relationships into a healthy state that's worth the hard discussions about it.
There are 2 people involved, the person who is struggling and the one who is 'healthy'. However in some cases, like ours, both may struggle with Mental Health issues which creates more conversations to be had.
The one very key and important distinction when it comes to Roles and Responsibilities is that the one who is'healthy' one is not qualified to provide the proper help and guidance. That is, of course, unless they are a trained professional. But that's an edge case situation.
It is the Responsibility of the one who is struggling to seek the proper care and counseling, and it's the Role of the "healthy" one to provide whatever support is needed.