Combining any two signs will often produce a distinctiive third sign, like the blending of two colors that produces a third. This is based on the aspect relationshhip of the two signs. Only in the case where Aries is the first sign does the second sign retain its own identity. This is because it is Aries' nature to EMPOWER any other sign.
Example 2: Aries + Taurus = Taurus(2nd house aspect)
Example 3: Aries + Gemini = Gemini(3rd house aspect)
Example 5: Taurus + Taurus = Taurus(1st house aspect)
Example 6: Taurus + Gemini = Taurus(2n house aspect)
Example 7: Taurus + Scorpio = Libra(7th house aspect)
Example 1: for someone with Sun in Leo
Any other planets in Leo(Mercury, Venus, etc.) will have an Aries or first house effect for this native, since they will reinforce his solar qualities. Virgo planets will have a Taurean or second house effect. Libra planets will have a Geminian or third house effect. And so on.
Example 2: for someone with Sun in Aquarius
I have often noticed, for example, Sun in Aquarius natives who appeared to exhibit very Taurean qualities, yet had no planets in that sign. Then I discovered that they had two or more planets in Pisces, which is the second house for Aquarius, and which apparently explained their seemingly Taurean qualities. Aries planets would give them a Geminian quality, Taurus planets would give Cancerian qualities or inclinations, and so on.
This sign blending works equally well with the Rising sign, the Moon, or any other of your planets. Each planet, in effect, has its own set of houses, so that twelve separate charts(using the whole sign house system ) can be drawn up, and each appears to yield equally conclusive results, dispelling the notion that the Ascendant is the only first house significator(although it is perhaps the most salient one).
Sign blending also reveals that the zodiac signs or qualities are a spatial phenomenon. In other words, it is the particular SPACE a sign occupies in a sequence that gives it its power or identity. Aries is Aries because it occupies the first space in a sequence. Taurus is Taurus because it is second and so on. If you align twelve objects or individuals in a sequence, the first object or person will take on Arian characteristics or qualities, the second Taurus, and so on. This applies to numbers and letters as well.