Apparently, feeling under the weather does wonders for character progression. My Lancer and Berserker are both 23, and my Warrior is around 13. I haven't touched Slayer, Sorcerer, or Archer yet. I kind of want to reroll my Warrior, but I used the Founder's mount on that character, so I guess I'm stuck with her. I should have thought about that before using it.
Also, I grabbed one of the 100% EXP bonus things from the cash shop for yesterday. They're character-specific, which I didn't know at the time. I thought it was account-wide, and I could get a bunch of characters out of the noob island.