How are you tonight
Your friend is lucky to have a friend like you
I am not sure that your friend is experiencing depression
Depression is characterized by episodes of all-encompassing low mood accompanied by low self-esteem and loss of interest or pleasure in normally enjoyable activities. This cluster of symptoms includes suicidal ideation, feeling hopeless, negative thoughts, or thoughts of death, feeling tired being angry.
Your friend does not have all the symptoms that are characterized by the dissorder but he has some of them. Dealing with childhood trauma may give someone the inability to trust, no skills in communicating and expressing feelings.
The best things you can do is to be there for him when he needs you. It may take him time to open up. I think he will need you to stay strong. Don't push him or treat him like he needs something. Just do the things you do with him. He will eventually open up to you. Tell him you are there if he ever wants to talk. Invite him to just spend time doing things you both enjoy.
I am glad he is in therapy.
I wonder if those symptoms are what you see with your friend.
In any case I think you are right to have reservations about this person. You can only tell if you want more than this person can offer.