Part of it is consistency. Showing up, being useful, caring about the outcome as much as the people you're working with do. But the deeper part is curiosity. The best working relationships are ones where both sides are genuinely interested in how the other thinks.
Where the exchange of perspective goes beyond the project at hand and into the broader questions of where the business is headed, what the market is doing, and what opportunities are emerging.
That kind of depth takes time. It accumulates through hundreds of conversations, shared decisions, and moments where both sides chose to go deeper when they could have stayed surface. The relationships that reach that level tend to last, and the work that grows from them reflects the depth both sides have put in.