In a holographic theory, an insertion of an operator with scaling dimensions \Delta ~ N^2 leads to backreaction in the bulk and creates a new geometry. I will first talk about such huge 1/2 BPS operators in N=4 SYM and compute their protected three point functions. For certain classes of operators like determinants and products of determinants, we can analytically compute the three point functions. The bulk duals of the two point functions are Lin-Lunin-Maldacena geometries, in which the one point functions of light operators depend sensitively on the details of the background. I will then talk about a simple two-matrix model which, like classical black-holes, exhibits universality at strong coupling such that light probes are only sensitive to few coarse grained pieces of information. The talk will be based on arXiv:2508.20094 and arXiv:2507.21207