Talk is a special command in the Fire Emblem series that allows playable characters to initiate a short conversation with their fellow allies, Other Units, or sometimes, Enemy Units while on the field. Usually, it appears in the menu for a specific character when he/she is adjacent to another unit that can be spoken to. Talks may be initiated by either character to start the conversation, or they may be entirely one-way. It most commonly appears when a character is able to recruit an enemy from the opposing side or an Other Unit, but it can also appear between two player units to reveal hints for gameplay, character development, or to receive benefits (such as stat increases or free items, especially in Genealogy of the Holy War). Also, in Rekka no Ken, certain pairs of characters with an A-level support can have unique conversations that take place in several chapters of the game, prompted by the Talk command. After talking, the recruited person(s) can still move and/or attack, even if they already moved as an enemy unit.
Player characters that are able to talk to an NPC unit in order to recruit them are usually mentioned by the recruitable characters themselves (for example, in Path of Radiance, Makalov mentions his sister Marcia, when he first appears in Training, who is the only one that can talk to him). Sometimes, the recruitable character encounter the player character themselves before the chapter, as seen in Sacred Stones, where Joshua accidentally bumps into a fleeing Natasha in Chapter 5. If the game doesn't hint at any specific characters being able to talk to a recruitable character, it is usually the main lord who can talk to him or her.
Occasionally, merely talking to a recruitable character isn't enough to recruit them. Some characters must be paid by the character who speaks to them before they agree to join. For example, in Genealogy of the Holy War, anyone can talk to Beowolf, but he won't be recruited unless he is paid 10,000 Gold. Similarly, Farina in Rekka no Ken must be paid 20,000 Gold initially and Volke in Radiant Dawn demands 3000 Gold for his services. Also, while talking is sometimes required to recruit a character, they may not join until later (for instance, Jaffar will join in the subsequent chapter if Nino talks to him during Battle Before Dawn).
The command is not exclusive to playable characters; enemy and NPC units are sometimes able to talk to player units of their own accord. In rare cases, this can be the only way a certain character can be recruited (e.g. Clarine from Fire Emblem: Binding Blade can only be recruited by letting her, as an NPC, talk to Roy.)
In Fire Emblem Awakening, it is possible to recruit Gaius,Tharja, Libra and Gangrel by having Chrom talk to them (thrice in Gangrel's case) while battling alongside or against them in Chapters 6, 8, 11 and Paralogue 18 respectively.