robin makes her decision in chapter 31 (endgame ship mentioned in chapter 32 beginning notes)

Steve rolls his eyes, gives Eddie a look of affectionate exasperation. ‘How are you gonna fuck me if you’re mad at me?’ That makes Eddie laugh against his will, it just kind of punches out. ‘Oh believe me, I’ll manage.’ He locks the door. The candles burn steady. The window is open. Sex magic is dangerous.