Full Idea
Selfhood in my sense comes for free once you have a conscious intentional being capable of engaging in free actions on the basis of reasons.
Gist of Idea
An intentional, acting, rational being must have a self
Source
John Searle (Rationality in Action [2001], Ch.5.II)
Book Reference
Searle,John R.: 'Rationality in Action' [MIT 2001], p.145
A Reaction
The concept of an 'action' is probably the thing that most clearly needs a self, because it implies co-ordination and purpose, and there must be some item which benefits. Personally I think you can drop 'free actions' and still have a self.