He knows what he's doing. What he's doing with the drugs, with the tea, with the clinic, with Mrs Fitz, with the receptionist, with the gas, with his family, with the masks. With everything. He's planning, he's planned and everything is going according to plan. But plans change.
With big things, with little things, plans change.
Befriending the receptionist, plans change just a bit.
Terrible headache (too much tea? too many drugs? not enough?), and plans change.
Argument with the girlfriend, plans? Oh, they change. Maybe the drugs taper down a bit. Maybe they go up.
Meeting the artist, gassing the artist, hiring the artist, gassing the artist. Plans change.
Playing nice with an Arkham staffer, or something like it, and plans change.
If Harvey escaped, plans would change. The plan might completely change. The plan might not be the plan anymore. Maybe there's a new plan, a better plan. Maybe Harvey has a plan.
Judah Stark is, if nothing else, completely adaptable. After all, he's not his brother.