  Proton-proton differential and total cross sections provide information on
the energy dependence of proton shape and size. We show that the deviation from
exponential behavior of the diffraction cone observed near $t=-0.1$ GeV$^2$,
(so-called break), both at the ISR and the LHC follows from the $t$-channel
two-pion loop contributions, imposed by unitarity. By using a simple Regge-pole
model, we extrapolate the "break" from the ISR energy region to that of the
LHC. This allows us to answer two important questions: 1) To what extent is the
"break" observed recently at the LHC a "recurrence" of that seen at the ISR
(universality)? 2) What is the relative weight of two-pion effect to the vertex
coupling (Regge residue) compared to expanding size (pomeron propagator) in
producing the "break"? We find that the effect comes both from the Regge
residue (proton-pomeron coupling) and from the Regge propagator. A detail
analyses of their balance, including the correlation between the relevant
parameters is presented.
