A system for presenting a mixed media narrative, said system comprising: (a) a media interchange linker arranged to: (i) receive a mixed media narrative comprising a plurality of medium expressions (62, 66); (ii) define for each medium expression (62, 66) a respective succession of segments (64, 68); (iii) compare the segments of a first medium expression to respective segments and associated metadata of a second medium expression; (iv) adding datum to each segment of the plural medium expressions of the mixed media narrative linking a segment of the first medium expression to one or more segments of the second medium expression; (b) a memory (30, 34) storing data, the memory configured to be accessible by a data processing unit, said data including: (i) a segment of the first medium expression; and (ii) a segment of the second medium expression and a first datum identifying said segment of said first medium expression as substitutable for said segment of said second medium expression; and (c) a data processing unit further arranged to: (i) receive a request for the mixed media narrative presentation; (ii) access data stored in said memory (30, 34); wherein said data processing unit substitutes said segment of said first medium expression during a presentation of said second medium expression if a preference datum expressing a user preference for said first medium expression is received by said data processing unit and if said first datum identifies said segment of said first medium expression as substitutable for said segment of said second medium expression, and wherein the preference datum determines which segments of the mixed media narrative to transmit to a user's computing device for presentation. (a) a media interchange linker arranged to: (i) receive a mixed media narrative comprising a plurality of medium expressions (62, 66); (ii) define for each medium expression (62, 66) a respective succession of segments (64, 68); (iii) compare the segments of a first medium expression to respective segments and associated metadata of a second medium expression; (iv) adding datum to each segment of the plural medium expressions of the mixed media narrative linking a segment of the first medium expression to one or more segments of the second medium expression; (i) receive a mixed media narrative comprising a plurality of medium expressions (62, 66); (ii) define for each medium expression (62, 66) a respective succession of segments (64, 68); (iii) compare the segments of a first medium expression to respective segments and associated metadata of a second medium expression; (iv) adding datum to each segment of the plural medium expressions of the mixed media narrative linking a segment of the first medium expression to one or more segments of the second medium expression; (b) a memory (30, 34) storing data, the memory configured to be accessible by a data processing unit, said data including: (i) a segment of the first medium expression; and (ii) a segment of the second medium expression and a first datum identifying said segment of said first medium expression as substitutable for said segment of said second medium expression; and (i) a segment of the first medium expression; and (ii) a segment of the second medium expression and a first datum identifying said segment of said first medium expression as substitutable for said segment of said second medium expression; and (c) a data processing unit further arranged to: (i) receive a request for the mixed media narrative presentation; (ii) access data stored in said memory (30, 34); wherein said data processing unit substitutes said segment of said first medium expression during a presentation of said second medium expression if a preference datum expressing a user preference for said first medium expression is received by said data processing unit and if said first datum identifies said segment of said first medium expression as substitutable for said segment of said second medium expression, and wherein the preference datum determines which segments of the mixed media narrative to transmit to a user's computing device for presentation. (i) receive a request for the mixed media narrative presentation; (ii) access data stored in said memory (30, 34); wherein said data processing unit substitutes said segment of said first medium expression during a presentation of said second medium expression if a preference datum expressing a user preference for said first medium expression is received by said data processing unit and if said first datum identifies said segment of said first medium expression as substitutable for said segment of said second medium expression, and wherein the preference datum determines which segments of the mixed media narrative to transmit to a user's computing device for presentation.