Mercere the Founder established this tradition of selfless service to Ordo Hermei after he lost his Gift. He dedicated his efforts to supporting Ordo Hermei in any way he could, and trained unGifted apprentices to do the same. This tradition was confirmed by Tribunal Grandis as a special privelage of Domus Merceris; and Caduceatores traditionally have a red head garment (cap, wimple, bonnet, etc.) as sigillum to honor the founder Mercere. By tradition, un-Gifted Merceris do not vote their sigilla, however.

Although Caduceatores do not possess the Gift and thus lack the ability to perform Hermetic Magic, they are not entirely without mystical ability. Many possess supernatural talents of one form or another, and some possess truly impressive abilities of this sort. Additionally, most Caduceatores are entrusted with enchanted devices to assist them in their duties. These devices are typically subtle effects to aid in travel or the transmission of information.

Caduceatores perform a variety of services for Ordo Hermei. Many are messengers and heralds, carrying correspondence and texts from conventum to conventum, or serving as formal witnesses for various matters. Others, known as Latruncalatores, serve as brokers and traders of vis and mystical items. Praevii and Cruentores serve as guides and escorts, or act as custodians and guardians for sites of significance to Ordo Hermei. Last but not least, Ostiarii serve as custodians for Portae Merceris.