親しむ
したしむ · shitashimu · JLPT N1 · verb-godan
to befriend
🐶 親 (close, intimate) + しむ (verb ending for doing it) = to make oneself close to
親しい (shitashii) means close or friendly as an adjective. Adding the しむ verb ending turns it into an action: to become close to someone, or to befriend them.