Fighting

Fighting is the most negative social interaction in all games in The Sims series. When two Sims dislike each other enough, they can start a full on fistfight.

When fighting occurs a cartoon-styled cloud of smoke will appear and obscure most of the fighting. Sims with higher Body or Athletic skill  skill are more likely to win the fight. A police officer and a burglar will fight if the police are summoned during a burglary.

The Sims
In The Sims, the cloud of smoke will completely obscure the fight.

If a Sim loses a fight, they will leave the neighborhood forever. Children can also have fights, but they will never leave town if they lose.

In The Urbz: Sims in the City, Fight can be chosen regardless of relationship.

As the Fight social type did not exist in The Sims and The Urbz: Sims in the City, Attack/Fight was a Mean Social.

The Sims 2 and The Sims Stories
Fights in The Sims 2 and The Sims Stories are a little more graphic and violent. Sims are now visible through the cloud of smoke, and will use a wide array of professional and comical fighting techniques. Sims with higher body skills are more likely to win fights.

During a fight, other Sims will react based on their personality. Mean Sims will taunt the fighters, nice Sims will be concerned, and shy Sims will run and hide. If one Sim cheers for a certain Sim in a fight, he/she is more likely to win.

Beginning with Nightlife, a fight can trigger fury. This can also happen in The Sims Stories.

If a Sim catches their children fighting, they will lecture the child.

After a fight, the Sims involved get a memory of winning or losing a fight.

In The Sims 2 and The Sims Stories, Attack is a Fight social instead of a Mean social.

The Sims 3
Fighting returns in The Sims 3 with a few changes. Besides high Athletic skill, Sims with the Evil or Mean Spirited traits are more likely to win fights. On the other hand, Cowards and Losers are less likely to win fights. The Martial Arts skill improves winning chances even more, with a 100% success rate if the other Sim has no Martial Arts skill. Other traits like Brave, Good, Lucky and Unlucky traits also determine fighting availability and success.

If a Sim wins a fight, they will receive the "Winner" moodlet. If they lose, they receive the "Humiliated" moodlet.

Sims with the Mean Spirited trait may choose to "Beat Up" a Sim as well as use any Fight or Mean social.

If the Sim is not Mean Spirited, the social is "Fight". If the Sim has the Mean Spirited trait, the social is "Beat Up". Like other Mean and Fight socials, the Sim can be kicked out if visiting. With Late Night, the Sim may also be Publicly Disgraced. Also in Late Night, Sims can start a brawl at a nightclub. Brawls are like a regular fight but it can involve more than two Sims and will last for longer (usually three times the duration of a normal fight).

If Supernatural is installed, Sims with the Proper trait have the interaction "Give (Sim Name) What For". If the Proper Sim is successful he/she will harass the other Sim before leaping on them and fighting as normal.

Sims with the Proper trait cannot properly initiate fights, or attempt to defend against burglars even if they have the Brave trait. Sims with the Good trait cannot initiate fights at all, but they can still get involved in them, as well as win (albeit much less likely).