Return charts square/conjunct/opposite natal planets

1
How does one interpret it when a planetary return chart makes an exact aspect to another planet in the natal?

For example, I have a friend whose upcoming Venus return chart figures an exact conjunction of his return Mercury making a conjunction to his natal Jupiter. In the same chart, he has his return Mars making an exact square to my natal Saturn. For both aspects they are on the same degree.

Since we're good friends, I know I'll factor into his life somehow. But how does one interpret these aspects? I know in the past another one of my good friends had her solar return Venus exactly sextile my Sun.

2
I say this every time I get the chance: the best book on solar returns is Book 23 of Morin's Astrologia Gallica. Unfortunately, the reader has to be familiar with Book 21, in order to benefit from 23.

Anyhow the theory runs this way. We always start with the nativity. Each planet represents potential in the life. When the return planet conjuncts the natal planet, and the tighter the orb the more powerful the result, it indicates that this year that planet's potential will manifest. This is particularly true if the conjunction occurs in the same house as the planet occupied in the nativity.

With Venus, the conjunction is about all you'll get - maybe a sextile. However with other planets, the square means the potential will work out with difficulty and the opposition means the return planet will work against the potential of the natal planet. The soft aspects, sextile and trine, are usually less prominent unless other factors in the chart bring something about.

Watch the angles particularly with Venus and Mercury since when the angles repeat, they might be in the same house and sign as they were at birth. The angles repeating is important as the natal planets rule the same signs they did at birth. If the angels are reversed, the natal planets work against their potential as they rule the opposite signs they rule in the nativity.

In short the nativity shows us the potential, and the returns show us when that potential will be realized and/or when that potential will be thwarted.