Single Point of Failure
As a technical manager, the last thing I want to be responsible for is a high profile software product that has a single point of failure (i.e. the single expert that "owns" it). My first move would be to understand the application then look to mitigate my risk.
In an economic downturn I might be looking to cut costs and eliminate a high cost employee in favor of an outsourcing solution. I would want to gather as much information as possible without giving out much until I could determine the course I want to take. Very few managers want to know applications from the inside out to look good - that isn't their job. The best move of the expert is to try to develop a candid relationship with the manager with the knowledge that the manager isn't going to share with you everything he knows but you are obligated to share everything you know about the application. Don't forget who you work for. Withholding information is the quickest path to finding yourself looking for a new job.
