I know very little about synastry charts. My brother has been on my mind a lot. We are practically strangers. I left home at 17 and have lived opposite sides of the US and then I left the USA.
We are siblings.�� So just curious what this chart says. I found one interpretation that states the predominate aspects are in conflict. I am the outer circle
This is a very interesting topic. I had a similar "stranger relationship" with my own younger brother.
Normally the questioner is in the inner circle - because mostly this TOB is accurate and well known and because of house cusps only shown for one person - and the questioner is of more importance as he has the question here. Perhaps you could be so kind to get the vice versae version synastry chart in here as well ?
Important is also to know that each synstry is only as good as the natal aspects and planet energies are coming along into a synastry effecting the other part's planet energies. The best trine cannot evolve it's best flow if it acitivates a hurting part in the other chart.
If your brother's TOB is accurate - your brother has a zero degree leo AC - between two signs and born like between the two parents in his life. Like "called" or feeling the inner order to rescue their marriage and the relationship of his/your parents. Sitting between two chairs in his childhood - not knowing where to take place to stay self-protected.
Leo risings mostly have issues with own father - what is for a man a more difficult affair to handle than for a women. Pluto rules his 5th house father - a strong intense influence from father on him with 4 planets in his 5th house. Pluto as ruler of his 5th is in communication house 3rd and he might have experienced his father as verbally very dominating and demanding very high standards of perfection on him.
Your brother in his childhood had to learn early to hide himself and to be more silent with his mercury ruling 3rd house in 6th house (=learning to adapt to outer influence and experience) in semisextile with neptune in his 5th. To avoid a king's competition with your /his father.
This also comes along into your synastry - even if you experienced your childhood and parents different.