Clemens first appears working in the garden. In Stage 2, he is greeted by Caecilius' merchant friend, and carries the wine when Caecilius and the Merchant eat dinner. In Stage 6, Quintus saves Clemens and Grumio from being attacked by a dog.
In Book 2, Quintus tells Salvius about how he escaped from Pompeii with Clemens and set him free. They traveled from Pompeii to Naples, then Athens and finally Alexandria.
Clemens is by far the most alpha out of all the freedmen, as he astonishes the guards of Eutychus' workshop.