I understand the default behavior of NHibernate is to detect changes to entities and automatically persist them. How would I go about changing this behavior so only explicitly requested entities are persisted? Would this require a new implementation of ISession, can it be done by using the FindDirty method of an interceptor or am I missing the best method? Or is NHibernate not really suited towards this?

I went the route you're looking at and discovered that it's not really a good idea. If you don't want an object's state tracked then either don't persist it, or, after it's persisted or loaded then remove it from the session or close the session.

If you want to choose to re-persist changes later you can re-associate the transient object with a session using SaveOrUpdate to get the changes into the database.

Cheers,

Symon.