When I'm joining a new organisation, I want to be useful as early as possible. I record what I observe until I get used to the new environment. Chances are my observations can turn into documentation or change of process that will make onboarding easier for the next newcomer. I want to prove myself, to show what I can do and be given responsibility.
When I'm onboarding somebody else, I want them to feel welcome and heard and seen, to show them we can work together well. I hope to gain their trust, so that they feel safe giving feedback.
When I'm offboarding someone, I need to pretend to not trust them, even though I do. I follow a checklist to revoke their access to services, information and infrastructure. I make sure that neither they, by negligence, nor a third party, by malice, can harm the organisation with forgotten accounts or elevated privileges.
When I'm offboarding myself, I try to share my knowledge well in advance, so that nobody needs me when I'm gone. I delete my own accounts and check that nothing breaks and nothing is lost. I give the team time to transition.