Crimson's mask is what it is, but since the Kingdom Hearts games and the Fullmetal Alchemist animes show every character's expressions, I figured Crimson should have a chart of expressions. Realistically, his mask wouldn't (or shouldn't) show his emotions, but if Crimson appeared in a future anime or game relating to Fullmetal Alchemist or Kingdom Hearts, I'd like his mask to move it's brows like on the drawings...
1. Normal Face (used for scowl, scheming, speeches and serious)
2. Sad Face (used for sarcasm and loneliness)
3. Annoyed Face (used for annoyance, being bored and disappointment)
4. Excited Face (used for eagerness, joy and success)
5. Scared Face (used for fright, shock, heartbreak and being worried)
6. Secretive Face (used for keeping secrets, acting naive and bargaining)
7. Angry Face (used for rage, infuriation, loss and laughing)
8. Sleepy Face (used for tiredness, lazy and sleeping)
© Kingdom Hearts and Fullmetal Alchemist are both licensed by Square-Enix. The secondary licenses for both franchises are Disney (Kingdom Hearts), Aniplex, Bones Inc., and Funimation (Fullmetal Alchemist).