A display medium for an electrophoretic display device includes a liquid system, at least one thermally reversible gelling agent, and at least one set of particles exhibiting a color. Inclusion of the gelling agent enables an image formed in the display device at an elevated temperature of about or above the melting point of the gelling agent to be fixed in a gel state, e.g., at temperature of about or below a gel point of the gelling agent. The image thus has stability, even in the absence of an applied electrophoretic field.