Maybe something along the lines of balance.
Balancing Act
Balancing Jack
Then each title could be along the lines of
trike a balance, balancing act, perfect balance.
His early days were more about retribution; punishment must fit the crime; use your car to destroy, he destroys your car. Throw things off the overpass to kill, get killed being thrown off the overpass. Something along the lines of retribution?
Early jack was about fairness. No grown man should have to stand in his lawn and cry, the unfairness of it ate at Jack.
Fair Play as a series; and then work Fair into all the titles of the books.
Jack's rage has always been his fuel. He has to get angry to act. He is most dangerous when he is enraged. Maybe something about coldfire, stoke the flames, burning anger. You could watch Jack's struggles to mature and keep that anger in check and always fail gloriously.
At this time in his life, he is developing towards adult Jack. He is shaping the attitudes that lead him to create a nation of one, to become a nonentity, but not there yet. We will start to see the situations that led him to want the life he will create for himself. Independence is way too cheesy, but maybe along the lines of liberation or control of your destiny or control; the one thing Jack wants most and acheives least.
Jack always works in the shadows. Hiding in Shadows, Shadow Master, Stealing Shadows, etc.
Same thing could work with Secrets.
I am just thinking out loud, the previous ideas are awesome. Just wanted to take this in a new direction for giggles.