In the console Sims 2, Fears were in red while wants were... I think green (except the mandatory Gold Wants). Red is also associated in real life with frightful things like bloodshed (and by extension, death), monsters (red glowing eyes), devils and demons, fire, etc. A dark or muted shade of red, distinct from the one used for Anger, could be a good option. Most of the other colours have been repeated. Blue (Sad, Inspired & Confident), Pink (Playful & Flirty), Purple (Focused & Dazed), Yellow (Energized & Embarrassed),. I think Green may be used for something other than Happy, but I forget. As far as I'm fairly certain, only Orange (Tense) and Red (Angry) haven't been used more than once.