I can't say that I've had experiences with "Energy Vampires", but I have had instances where people seem to be drawing Reiki energy from me without me consciously 'turning it on'. In these situations, I usually just open myself to the Reiki Pool and allow myself to be a clear channel for Reiki energy. If the person needs it and continues to take the energy, I still receive a healing for myself as I allow it to flow through me. This should usually combat the problem of someone 'sucking your energy', as opposed to accepting the Reiki flow. You should be left calm and energized, rather than tired and drained.
Good luck!
