Walter Pater's late-nineteenth-century literary genre of the imaginary portrait has received relatively little critical attention. Conceived of as something of a continuum between his role as an art critic and his fictional pursuits, this essay probes the liminal space of the imaginary portraits, focusing on the role of the parergon, or frame, in his portraits. Guided by Pater's reading of Kant, who distinguishes between the work (ergon) and that which lies outside of the work (the parergon), between inside and outside, and contextualised alongside the analysis of Derrida, who shows how such distinctions have always already deconstructed themselves, I demonstrate a similar operation at work in the portraits. By closely analysing the parerga of two of Pater's portraits, ‘Duke Carl of Rosenmold’ (1887) and ‘Apollo in Picardy’ (1893), focusing on his partial quotation of Goethe in the former, and his playful autocitation and impersonation of Heine in the latter, I argue that Pater's parerga seek to destabilise the relationship between text and context so that the parerga do not lie outside the text but are implicated throughout in their reading, changing the portraits constitutively. As such, the formal structure of the parergon in Pater's portraits is also a theoretical fulcrum in his aesthetic criticism and marks that space where the limits of, and distinctions between, art and life become blurred.