The Grand Trine Kite starts with a 3-point Grand Trine. A fourth planet has an opposition aspect (180°) to one of the planets, and a sextile (60°) to the other two. The opposition forms the "spine" of the Kite. There are several possible ways that the opposition aspect can affect the Grand Trine figure.
Since trine aspects (120°) allow things to come easily, the potential can be largely untapped. The opposition aspect creates stress, struggle and conflict—although it is also dynamic and motivating. The tension may make it necessary to draw on the potential in the trines. In fact, the natural ability of the trines can provide a valuable resource for working with the opposition issues, providing a positive outlook, natural ability, and an easy-flowing source of energy.
The opposition aspect often brings conflict, polarization, disagreement and stress, although it is also dynamic and motivating. It is a challenge to be triumphed; a problem to be solved; a disagreement to be negotiated.
The two planets in opposition are like two apex planets and therefore perform key roles how the energy flows. The Grand Trine planet that has the opposition may activate the tension or conflict, which is expressed or acted out through the other opposition planet with the sextiles. The apex planet with the sextiles may also act as a grounding principle; a kind of lightning rod that is struck by the tension of the other apex planet.
Another view is that in order to gain positive and productive access to the Grand Trine energy, the conflict of the opposition planets must be resolved and mastered mastered first.
For more information, you can read my article about the Grand Trine Kites of 2007.