The base game only has portraits for unique characters.
You need to get one of the created portrait mods from this forum or another and drop them into your "%AppData%/Roaming/Strive" portraits and bodies folders. This will give you the pictures, then use either the "use random portraits" in the game or the mod on this forum to have them applied to your slaves. Have fun!
Kaito it's written in about 10 places on this forum.
Are you on Windows?
If so, go to the folder "%AppData%/Roaming/Strive". Hit the windows button, type that, press enter. If you can't figure that out, go to "C:\Users\USERNAME\AppData\Roaming\Strive".
In that folder, you'll find "portraits", "bodies", and "mods". Put the portraits in "portraits", bodies in "bodies", and mods in "mods".
For images, it may now find them automatically, or you can choose them by going Customize -> Choose image for each slave.
For mods, open the game, press "mods", activate the ones you want, then hit enter and it will exit the game. Now restart and TADA you have mods.
