A protégé is an associate of a member of the Order of the Pelican, similar to the relationship between Squires and Knights or Apprentices and Laurels. Protégé is a job/relationship description, and not a title. Therefore, one should be addressed as "So-and-so, protégé to Mistress/Master Heliumhand", rather than "Protégé So-and-so".
In some other kingdoms, it's common for a protégé to wear a yellow belt - and it is becoming common in An Tir. See Sumptuary Laws for information on protégé's belts.
Like other peerages, relationships may vary greatly, depending on the Pelican and protégé involved. They might be formal teaching arrangements, more advisory in nature, or be very informal. It is best to take your time and only enter into a relationship that will work for both of you.
See Category:Protégés for a list of protégés in An Tir.