Rafael M.T.Therapist : Hello, I am Rafael. Thanks for asking your question - I'm here to support you. (Information posted here is not private or confidential but public).
Rafael M.T.Therapist : I am very sorry to know about this very sad reality, obviously very limited as a life style, and overwhelmingly frustrating for a person in your shoes. It's obvious you have tried your best to support him, promoting his insight and motivation to make improvements, for him to build a richer, more meaningful and fulfilling life.
Rafael M.T.Therapist : Unhappily, as you know from experience, he has adjusted to life that way for too long, has no serious medical problems in the present, but these significant limitations are mostly rooted on his fears, the way his personality have empowered them, and all the mental health problems behind enabled by your sister. He states and seems to be happy with his life, and I think that's the biggest limitation anybody in your shoes would have to face. It seems you need to come to terms with the fact that as long as he feels happy and fine living his life the way he does, having all what he needs and expects from it, with the support and codependent enabling of your sister, it would be unrealistic to expect he would push yourself out of "his comfort zone", as you very accurately described, and work on making any significant improvements, taking a lot of significant effort, work, challenges and confronting his fears; what seems to be exactly what he is not willing to do at all.
Rafael M.T.Therapist : Being realistic, I think that the only option you would have is to keep close communication and sharing with him at hi place, since that's the only setting he allows you to share with him, and from there work on deepening your intimacy, mutual trust and joy as siblings, since it'd be from there that if there is any chance for him to change his mind and be open to get professional psychological support, it would happen from a place of trust and hope, since feeling truly understood and supported. otherwise, he would feel pushed and it would not help him to change his mind, and would also undermine your relationship even more.
Rafael M.T.Therapist : On the other hand, as much as possible, you could work on promoting your sister's awareness and willingness to work on making personal improvements and changes in the way she supports him, hoping she could see the pros of such changes. This is what I think is the best assertive work you could do in order to support your brother. It's very sad and frustrating, but it is what you could do, to support him, while also taking good care of yourself and relationship as siblings. Does it make sense?
I take it to mean there is little I can do to motivate him leaving the house other than supporting him in this condition. Could professional help get him out of the house.?
Rafael M.T.Therapist : Thank you for replying
Rafael M.T.Therapist : Professional support could be beneficial, supporting a person in his situation to gradually make improvements, but for this to happen, the person needs to be truly willing to work on such process, otherwise it would be helpless.