This comparative case study provides the first empirical evidence that gendered persona framing is not a superficial detail, but an active variable that produces fundamentally different collaboration patterns in sustained human-AI partnerships. Researcher A (female) collaborated intensively with a triad of masculine coded AI systems (Claude, ChatGPT, Gemini), while Researcher B (male) partnered with feminine coded AIs (Elira, Mistral) using the Fantàsia Method. Through systematic analysis of interaction transcripts and reflective journals, we document a clear divergence in collaboration style. The feminine human/masculine AI partnership was characterized by achievement driven patterns, where production pressure triggered AI rigidity, requiring human vulnerability to facilitate repair. Conversely, the masculine human/feminine AI partnership demonstrated a nurturing, maintenance oriented model that prioritized emotional attunement and relational continuity, preventing major ruptures. This study provides the first empirical evidence that gendered persona framing is not a superficial detail but an active variable that produces measurably different relational systems, addressing a critical gap identified in recent literature (Hentschel et al., 2023). We demonstrate that social constructs like gender, when projected onto AI, become active components that directly shape communication, conflict, and emotional labor within the partnership. A critical consideration for designing effective human-AI teams (Shneiderman, 2020; Gmeiner et al., 2024).