Various systems and methods relate to an adaptive chair system having (i) a stowed mode in which the members of the chair frame are contained within a compact flexible multi-function bag (MFB), and (ii) a deployed mode in which the MFB is adapted to releasably couple to an arm of the chair to provide a multipurpose accessory chamber. In an illustrative example, the MFB may, for example, fold in on itself in an accessory mode. The MFB may provide various utilities for hikers, for example, by providing a case to receive an inflatable bladder so as to form a pillow. The MFB may receive a thermal liner adapted to maintain, for example, food or beverage temperature. Various embodiments may advantageously provide a rugged, water resistant MFB system in an ultralight form factor that serves as a multipurpose accessory (e.g., to store items), yet provides a compact, adaptive chair frame containment.
