Caerdroia illustration [fullsize]
The Doctor is split into three versions, representing different aspects of himself. The calm, responsible, reasonable, lecturing, boring one. The giddy, distracted, enthusiastic, naive, curious one. And, in his own words, the nasty one; grumpy, impatient, cruel, and quite capable of torture and murder.
There’s also a ball of string that makes a plot-relevant appearance, in case you thought that was entirely random. I just wanted to get across the personalities of each one in a metaphorical way, because this story is awesome, and how could I resist drawing three Eighth Doctors?