Software developers: what do you wish you knew/understood (more) about the product manager(s) you work with?

I'm preparing a talk 100% aimed at software developers working with a Product Manager. The goal is to shed some light on the nuances and challenges of the Product Manager (including where one usually misbehaves! 😉 ), in a way that (hopefully) allows you to:

• work better with one; and
• help one work better with you.