Intoxication. It could be an example of dynamic status effects. Depending on the substance and how much is consumed and individual tolerance levels it could have different effects.
Perhaps the... uh, increasing of attributes based around personality from the median? What I mean is, for example, let's say that we have two characters, one with a low aggression, one with a high aggression. Let's assume that the tolerance of each is the same.
So, after each character has the same amount of alcohol, the aggressive character would get more aggressive, while the shy character would get... shyer. This would be opposed to a system where both characters would be more aggressive, by merely adding a positive number to the aggression values.
To use numbers to aid this demonstration: Let's say the characters have aggressions of 7 and 4. After the same amount of alcohol, these characters may have new aggressions of 3 and 8, both "1" away from the average, which is 5. On top of this, you could have a system where you actually add a differing value derived from the difference from the average - For example, while a 6 may be increased to 7, a 9 may be increased to a 11. And, of course, tolerance can affect this also. Indeed, the consumption of alcohol may
permanently increase the character's tolerance by a small amount, if long-term simulations are viable.
Just a suggestion, take from it what you wish, but I think that with a social interaction simulation like this, such a feature could be very important.