The AdS/CFT duality maps supersymmetric heavy operators with conformal dimension of the order of the central charge to asymptotically AdS supergravity solutions. I'll show how by studying the quadratic fluctuations around such backgrounds it is possible to derive the 4-point correlators of two light and two heavy states in the supergravity approximation. I'll present some explicit examples in the AdS3 setup relevant for the duality with the D1-D5 CFT and discuss what we can learn in general about correlators among heavy pure states.