Pick two (multi)-curves on a surface. What can be said about the subgroup generated by powers of Dehn twists about the two curves? For twists about single curves a complete classification up to isomorphism is known and is determined by intersection number and twist power. For multi-curves with more components, the fourth powers of the twists generate a free group. I will present analogous results for groups generated by two Dehn (multi-)twists in $\mathrm{Out}(F_r)$, where the analysis is complicated by the absence of a standard topological model. I will also make connections to the question of uniform uniform exponential growth.