References to a character in the forums are as important as the impact a character will have around it. They aren't necessary for low profile, regular role characters, but are of the utmost importance to characters whose overall behavior can create a disruption in the status quo around them.
This reference doesn't have to be a story to a point, it can be a set of guidelines to that character's behavior so the community (the people who will be exposed to that character in game) can verify if those guidelines are something acceptable to them. It goes pretty much in the same lines as the proposition for a faction. People will want to know what ships are you using, why, what are you going to do with them, who you will be going to attack and why etc.
Considering this is an RP server, putting all that in a story is a good thing. To a character that is very much exceptional, a back story ceases being something optional to become something necessary. There's only so much you can accomplish through actions and communication in game. Even if you risk metagaming from other players, people will need to know how to react around your out of the ordinary character, it's a matter of respect giving as much information as you can to people so they know what's going on. Not doing will promote unnecessary and uncalled for grievances.
The more unusual your character is, the greater the chances of the game not being able to support you depicting it, so you have to complete the experience somehow. Creating an interesting and attractive story to do so can only be a good thing.
For that matter, players that play odd roles such as that of the Keepers, Dreygon's Mon'Star, mine and Zapp's ghosts and some others, they do have an obligation to the community to make these roles as clear as possible. That is only the first step and it doesn't, by any means, exempt these players from putting an even greater amount of effort into RPing these characters in game.