Things You'll Need
Instructions
Open "Nightmare Editor" to bring up the interface that edits "Fire Emblem 7" files indirectly, allowing you to perform the operations more simply.
Expand the "Editors" tab along the top of the window and choose "Character Editor" from the list of options.
Pick a character whose portrait you want to change from the drop-down menu on this tab. The information fields will load after a character is selected. Note that you can change main character, as well as secondary characters and generic enemies and NPCs (nonplayable characters). When changing a generic character's portrait, it will influence all of the characters of that type within the game.
Click "Browse" next to "Character Portrait" and select the file that you want to use in place of the original from the directory of your "C:/" drive that appears. The picture must have maximum dimensions of 50 by 50 pixels.
Press the "Save" button at the bottom of the window to apply the new picture to the game files.