in one's pocket
1. In one's power or possession, under one's influence. For example, The defense lawyer had the jury in his pocket. [Mid-1800s]
2. in each other's pockets. In very close proximity or mutual dependence, as in Bert and Harry work in the same office, live in the same house, belong to the same clubs-they're constantly in each other's pockets . [Mid-1900s]