As I wrote I Wish... I had a very vivid picture of what my characters looked like. My imaginary friends came to life... And then my editors read I Wish... and they came up with their own versions of Kira and Jack.
One particular friend of mine chose the following two actors to represent Jack and Kira.
For Jack she chose Alex Pettyfer (I am Number Four). She liked the seriousness and strength of his characters along with his shy romantic side.
For Kira she chose this particular picture of Emily Browning (Series of Unfortunate Events and Sucker Punch). She liked Emily's impish look and exotic eyes along with the methodical way she seems to solve problems she faces.