An overall look at this chart would suggest a potential for depression at certain times in the life; the oppositions and squares in the chart are pretty heavy duty. Saturn/Mercury depicts that it can be hard for him to see the positive in life; Mercury ruling the Desc shows he can have difficulties with socialization and communications with others. In these days it is important to factor in environmental factors contributing to disruptions in the brain chemistry as well, which can sometimes create mood disorders or bi-polar disorders as well. Sun opp Neptune shows that something is 'off' relating to his sense of personal Identity; does he suffer from low self-esteem? Does he flip back and forth between moods? Then, the oppositions are all contained within the outer square configurations adding further to his difficulties. Also of note, while you have Mars/Pluto square, your brother has Mars opp Pluto, and this gives a key to shared experiences in terms of the parental influence in the past...