Asanga and Vasubandhu were two brothers who played a significant role in the development of Yogachara Buddhism. They were born in a Brahmin family in the 4th century CE in Purushapura, India. They both were initially followers of the Sarvastivada school of Buddhism but later became prominent figures in the Yogachara school.

The relationship between Asanga and Vasubandhu can be described as a complementary one. Asanga was the older brother and was known for his deep meditation and spiritual practices. He was a skilled practitioner of the Yogachara teachings and was known for his ability to enter into deep meditative states. On the other hand, Vasubandhu was a scholar and a prolific writer. He was known for his intellectual prowess and his ability to articulate complex philosophical concepts.

Together, Asanga and Vasubandhu worked to develop and spread the teachings of Yogachara Buddhism. Asanga is considered the founder of this school of thought, and Vasubandhu is often referred to as the systematizer of Yogachara teachings. Asanga's deep understanding of meditation and spiritual practices, combined with Vasubandhu's scholarly abilities, proved to be a powerful combination in the development and propagation of Yogachara Buddhism.

One of the most significant contributions of Asanga and Vasubandhu to Yogachara Buddhism was the development of the concept of the "three natures." According to this concept, all phenomena have three levels of existence - the imagined nature, the dependent nature, and the perfected nature. Asanga and Vasubandhu's teachings on the three natures helped to explain the nature of reality and the role of perception in shaping our understanding of the world.

Another important aspect of their collaboration was the development of the Yogachara doctrine of the "storehouse consciousness." This doctrine states that all experiences and actions are stored in a deep level of consciousness, which influences our present and future experiences. Asanga and Vasubandhu's teachings on the storehouse consciousness helped to explain the concept of karma and its role in shaping our lives.

In conclusion, the relationship between Asanga and Vasubandhu was one of mutual respect and collaboration. They both brought their unique strengths and abilities to the development of Yogachara Buddhism, and their contributions continue to influence the practice and understanding of this school of thought. Asanga's deep spiritual practices and Vasubandhu's intellectual acumen were essential in establishing Yogachara as a distinct and influential school of Buddhism.