made-up Capt. Eden
As opposed to the real, not-made-up Janeway.
Made up for the Trek books, of course, as opposed to already shown on TV for seven years, you should know that there is a difference between a "paper" character and an official canon character who we have seen in action and have grown to respect and admire (and do want to see more of in print).
But they're all fictional constructs.

Whether it be Captain Kirk (my personal favorite), Captain Calhoun, Captain Janeway, Commodore Reyes, Captain Chakotay or Captain Eden... they are all fictional constructs there to service the story. There is no difference in their purpose.
Captain Chakotay commands Voyager and Eden is the mission commander. No different a set-up than we've seen episodes like A Taste of Armageddon, The Galileo Seven, Too Short a season and The Pegasus.
But never fear, Eden was clearly written with an exit strategy in mind. That way Voyager at some point can return the status quo 'in-universe' and out (no one buying Voyager novels). So you can pat yourselves on the back when Voyager quickly returns to obscurity thanks to a few who refuse to have their collective horizons broadened.
