Direct is a special command in Fire Emblem: Path of Radiance and Fire Emblem: Radiant Dawn that is only available in chapters with Ally Units. Direct allows you to control how the CPU handles Ally Units' actions. It can only be used by the leader of the player's army. It is comparable to the Order command.
Available Directing sub-commands
Both games feature the same four sub-commands of Direct: Roam, Halt, Avoid and Target.
Directing your allies to roam will let them do as they please. Usually, this means they'll charge into enemy lines and attack enemies as much as possible. It is the only sub-command of Direct wherein your allies will attack enemies or use staves. This is the default Direct.
Directing your allies to halt will mean they will not move at all.
Direct your allies to avoid to have them stay out of enemies' attack range as much as possible. This is the only Direct that differs between the two games; in Path of Radiance, your allies will move into a corner as far from the enemy as possible, while in Radiant Dawn, they will move as close to enemy lines as possible while still staying out of their attack range.
When selecting this Direct, you will be prompted to mark one tile on the map. Your allies will then move towards the selected tile.