Command Seals

Sealed Pact

Command Seals are one of the primary markings of a Summoner. Once a summoner forms a pact with a Servant they receive a set of Command Seals that appear as a mark on the back of their hand. Command Seals have the main function of securing the pact between the summoner master and the servant. As long as the Summoner still has one Command Seal, a servant can't willingly harm their master.   However, once the final Command Seal is used, the contract between the two are cut off and the servant's previous obligations are nullified. If the summoner still wishes to have the servant stay around, they may continue to supply them with magical energy, treating their servant as a familiar. The opposite can also very much occur though, for if a servant feels like their master has mistreated them far too much, the moment the last Command Seal is used may also the moment the servant proceeds to kill their former master.  

Compelled Actions

Besides marking the pact between the summoner and the servant, Command Seals also have several other uses as well. Some of them include:

• Forcing a servant to carry out a particular action regardless of their objections.
• Allowing a servant to activate their Noble Phantasm.
• Forcing a servant to enter or exit the ethereal plane, regardless of distance.

Lots of thought must go into using a Command Seal. The biggest risk of using a Command Seal would be to force one's servant to do something that they object to doing, such as killing a comrade or telling them to do anything that goes completely against their ideal(s). Careless usage of Command Seals in this sort of way is one of the ways that cause a relationship between master and servant to sour.

Representative Servants

When it comes to faction/representative servants, Command Seals work a bit differently. Because these servants serve under a faction, rather than under an individual summoner, the relation works in a slightly different way. A faction that is participating in the Holy Grail War are given a set of Command Seals that are more or less distributed amongst the faction leaders. So, if a large guild of mercenaries are inducted into a war, the Command Seals collectively appear on the hands of the main leader and their closest constituents. If need be, faction leaders that originally held Command Seals may transfer one or more seals to another individual of the same faction, such as the mercenary leader transferring a Command Seal to a captain that will be accompanied by a faction servant.