I find Ten rather easy to write. Probably because he has so many quirky speech patterns. Four comes pretty natural as well, which is odd I suppose, because he's supposed to be one of the harder ones to write. I can do Romana II but not Romana I. And Hex, of all characters, turned out to have a soft spot for my keyboard.

Then there are the ones I absolutely CANNOT write: One, for whatever reason, I cannot do him justice. And Donna, which annoys me, because I love her to bits.