In this partly expository monograph we develop a general framework for producing uncountable families of exotic actions of certain classically studied groups acting on the circle. We show that if L is a nontrivial limit group then the nonlinear representation variety HompL, Homeo`pS 1 qq contains uncountably many semi-conjugacy classes of faithful actions on S 1 with pairwise disjoint rotation spectra (except for 0) such that each representation lifts to R. For the case of most Fuchsian groups L, we prove further that this flexibility phenomenon occurs even locally, thus complementing a result of K. Mann. We prove that each non-elementary free or surface group admits an action on S 1 that is never semi-conjugate to any action that factors through a finite-dimensional connected Lie subgroup in Homeo`pS 1 q. It is exhibited that the mapping class groups of bounded surfaces have non-semi-conjugate faithful actions on S 1 . In the process of establishing these results, we prove general combination theorems for indiscrete subgroups of PSL 2 pRq which apply to most Fuchsian groups and to all limit groups. We also show a Topological Baumslag Lemma, and general combination theorems for representations into Baire topological groups. The abundance of Z-valued subadditive defect-one quasimorphisms on these groups would follow as a corollary. We also give a mostly self-contained reconciliation of the various notions of semi-conjugacy in the extant literature by showing that they are all equivalent.