Madrius Dark Sun
You are all welcome to come up with backup characters. There is no limit to the amount you create, but please make sure it is within your own realm of control.
Your characters can be swapped out. The easiest way to do this is make sure that your backup has some sort of connection with the current party, and you are able to work them into the story. This can be useful during leveling if your current character needs to travel somewhere specific for training, or spend extra time that party does not have the patience to wait around for. It also gives you a chance to explore different aspects of the campaign setting, or filling in role positions that would be beneficial.
I will allow one swap per level, and your backup character will start with the same XP as your primary character. I foresee this happening more in the future, perhaps at paragon and epic tier where you will be required to spend more time leveling.
I am still going to require journal entries for your backup characters explaining things such as powers, feats, and ability scores that are gained.
These rules are subject to change (as with everything else on the site), but for now this is it.