NOVELTY - Fueling a solid oxide fuel cell stack (12) in a fuel cell system (310) including a catalytic hydrocarbon reformer and a hydrocarbon cracker (360), involves passing a first portion of hydrocarbon fuel through the catalytic hydrocarbon reformer to generate a first reformate, where the hydrocarbon fuel has been 0-100% reformed; passing the first reformate through the hydrocarbon cracker to generate a second reformate, where a portion of any non-reformed hydrocarbon fuel in the first reformate is converted to methane; and supplying the second reformate to the solid oxide fuel cell stack.    USE - For fueling a solid oxide fuel cell stack in a fuel cell system including a catalytic hydrocarbon reformer and a hydrocarbon cracker (claimed).    ADVANTAGE - The method and system including reformer and fuel flow arrangement permits optimized fuel reforming at all power load levels of the fuel cell stack of 0-100%. The method/system shows highest fuel processing efficiencies. The system allows for full flexibility in fuel processing; and exhibits fuel efficiency over the full range of operating loads.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a solid oxide fuel cell stack assembly comprising a catalytic hydrocarbon reformer for generating a first reformate from hydrocarbon fuel; a hydrocarbon cracker in communication with the catalytic hydrocarbon reformer for receiving the first reformate and generating a second reformate; and a fuel cell stack in communication with the hydrocarbon cracker for receiving the second reformate. The catalytic hydrocarbon reformer is an endothermic reformer.    DESCRIPTION OF DRAWING(S) - The figure shows schematic flow diagram of improved, hybrid, solid oxide fuel cell (SOFC) system.    Solid oxide fuel cell (SOFC) stack (12)    Anode inlet (14)    Main fuel reformer (18)    Heat exchanger (137)    First portion of anode (140)    Hybrid, flexible solid oxide fuel cell (SOFC) system (310)    Hydrocarbon cracker (360)    Controller (362)    Actuators. (364)