In his introduction to I.4, the first story he tells, Dioneo expresses the opinion "that each must be allowed [...] to tell whatever story we think most likely to amuse." Consequently he will be granted the privilege not to follow the theme of the day and to tell instead the story that most pleases him, regardless of its consonance or dissonance with the others told in that day. In exchange, he will be the last of the ten narrators to tell a story. This positioning is significant because it is meant not to interfere with the pattern developed in a given day; on the contrary, Dioneo's privilege grants him a role of transgressor while at the same time, as an exception, reinforces the (narrative) rule that governs the Decameron.
Within the space of their paradisiac seclusion from reality, death and disease, Dioneo reminds the brigata of their mortality, their humanity in the face of stronger forces. His manner of narration is forthright and clear, as is his language. The puns he uses resonate immediately with the rest of the company because they refer to situations and feelings they can recognize in their own experience; indeed they are common to all human experience. Dioneo has an incredibly strong command of language in communicating with exact intention - he can do so without thought, "naturally," while the other members of the troupe are most recognizably self-aware of themselves in the position of narrator. For this reason, one could argue that Dioneo is, in actuality, the ruling narrator of the Decameron, disguising - and at the same time revealing - this role through his position each day as the final narrator. That he holds the greatest power becomes clear by way of his effective and confident storytelling.
Dioneo is the personification of freedom. He is an anarchic figure, though not an extremist. We should not forget the "urbanity" of the Decameron, and the crucial importance of social interaction among the members of the brigata. Absolute lack of conformity and compromise would mean for Dioneo isolation, as any social interaction requires some degree of conformity to or acceptance of the rules. Although he represents the "pleasure principle," Dioneo is also the embodiment of a social necessity, he is an integral part of the brigata' s "utopian" society. His narration - unfettered as it is by the thematic constraints imposed upon the others - could fairly be seen as a metaphor for a sort of "liberation of the repressed" within the framework of the Decameron, a safety valve for the frustrations and anxiety of his society at large.
Boccaccio's assignment of Dioneo as the ruler of the seventh day is significant because Dioneo represents a transgressive, though salubrious, spirit within the infinite potentiality of language. The infinite play in which literature engages mirrors an arabesque, or spiral, which regenerates itself in a constant re-centering, changing of balance, and movement in an infinite number of possible directions. The number seven signifies a chaotic tendency, transformation which is continuous and incomplete. The Thousand and One Nights imitates this process. This chaotic and disruptive tendency is echoed by the topic dictated by Dioneo for this day (the imposal of a theme notably runs counter to his own privilege): that of tricks played by women on their husbands, the ultimate transgression within patriarchal society. Trickery is characteristic of narration itself - an endeavor of which Dioneo is undoubtedly a master.
Dioneo is the ideal lover, a verbal Don Juan in the world of the Decameron (the man who loves to please women, the work's self-proclaimed implied readers). That he might represent Boccaccio's view of "natural" love is demonstrated by his song at the end of the fifth day. Indeed, his is the most sincere love song yet sung in the Decameron.