The need for a homotopy-invariant lower bound for the number of fixed points of maps of pairs arose because of Jiang's proof of the Wecken property for homeomorphisms of surfaces, in order to extend the result from closed surfaces to surfaces with boundary. Schirmer's relative Nielsen number not only furnished the appropriate tool for this purpose but lead to significant developments in just about every aspect of Nielsen theory. This talk will present a sample of these developments, including work (with Kelly) still in progress on the Wecken properties of boundary-preserving maps of surfaces.