Which character is introduced as a major figure in Dunny's adult life?

The character Magnus Eisengrim plays a pivotal role in Dunny's adult life as he represents a significant connection to the theme of identity and the search for meaning that pervades the narrative of "Fifth Business." Magnus is not only a magician and an illusionist but also a complex figure who embodies the qualities of transformation and the exploration of different selves that resonate deeply with Dunny's own journey. Their relationship illustrates the interplay between art, reality, and personal discovery, emphasizing how Eisengrim influences Dunny's understanding of his own life and the lives of others.

While other characters also hold importance in Dunny's life, such as Paul Dempster, who relates closely to Dunny's childhood and familial ties, or Leisl, who introduces elements of romance and complexity, it is Magnus Eisengrim who marks a profound influence as Dunny navigates his identity and explores deeper philosophical questions. Colborne, although a noteworthy character, does not have the same transformative impact on Dunny’s journey as Magnus does. The nuanced relationship between Dunny and Magnus serves as a crucial element in the overarching exploration of the themes presented in the novel.