  Stopping and regenerating a pair of single-photon pulses at adjacent
locations in coherently prepared Rydberg atomic ensembles are significantly
affected by their effective interaction mediated by Rydberg excitations, and
the similar processes can differ notably from the one exhibiting the common
Rydberg blockade as with the stationary propagation of multi-photon light beams
in the same medium. Based on the complete dynamics, we reveal the detailed
features in such processes by finding how the profiles of the involved quantum
fields evolve in various situations. The findings help to determine the proper
regimes for implementing photonic gates and transistors. In addition, we
discuss the non-adiabatic corrections associated with quickly changing control
fields, and illustrate a method that restores the photon pulses' original
amplitude during their retrieval unless they are heavily damped before storage.
