How do I turn a transaction into a relationship that lasts?

You know how to service an account. You answer when called, you deliver what's promised, you show up when something is owed. That is competence. It is not a relationship — it is a transaction that repeats itself and calls itself loyalty. A relationship survives the moment you have nothing to sell. It is built in small, unpaid attentions: the question asked when no deal is pending, the detail you remembered because you were paying attention, not performing it. You have been managing accounts. You have not yet chosen to know the people inside them. This is not charisma, and it is not a personality you either have or lack. It is a habit — practiced when it costs you something and returns nothing you can invoice for. Begin there, or do not pretend you are building anything at all.