Variation on a comprehensive theme

The main result concerns a bicategorical factorization system on the bicategory $\mathrm{C}\mathrm{a}\mathrm{t}$ of categories and functors. Each functor $A\text{xra}fB$ factors up to isomorphism as $A\text{xra}jE\text{xra}pB$ where $j$ is what we call an ultimate functor and $p$ is what we call a groupoid fibration. Every right adjoint functor is ultimate. Functors whose ultimate factor is a right adjoint are shown to have bearing on the theory of polynomial functors.