Loner (The Sims 4)

"These Sims become Happy when alone, do not receive negative moodlets when their social need is low, become Tense around strangers, and become Embarrassed more often by social rejection."

Loner is a social trait in The Sims 3 and The Sims 4. It conflicts with the party animal, dance machine and outgoing traits. Bob Pancakes, Hugo Villareal, Yuki Behr are the only pre-made sims that have this trait and on the wikia are categorized

Attributes

 * Loners find it harder to make new friends. Tense Loner.jpg
 * Loners receive the "Enjoying Solitude" moodlet which gives +1 happy emotion when alone. Embarrass Loner.jpg
 * Loners receive the "Stranger Danger" moodlet (+1 tense) if they are around strangers.
 * Occasionally, when loners interact with other people, they receive the "Socially Awkward" (+1 embarrassed) moodlet.
 * Loners never get a "Lonely" moodlet (+1 sad).
 * Nearby pets do not remove the "Enjoying Solitude" moodlet.
 * Loners will say the following when put into a rather large outing group: "This is more people than I can handle...I've got to get out of here!" followed by their feelings on the group outing. This occurs even with family members (tested with an 8-member group outing where two members were loners. After a few sim-minutes, both quit the group immediately leaving it a 6-member group). Another test used 5 siblings, and was a one loner. The single loner quit the group immediately leaving it a four-member group.
 * Loners will reject the "Woo!" interaction from Sims with the party animal trait.
 * Loners with the insane trait will never need to socialize with other Sims. This is due to the fact that not only will the social need decrease slower because of the loner trait's effect, but also having the insane trait allows them to use the "Talk to Self" interaction to raise their social need in addition to their fun need.
 * If a party is taking place in a different household within the neighborhood, the "Gossip" interaction may reveal the loner's disdain for parties.