Is it possible in Sims to play just a single character while other characters are controled by AI?
That is a very large topic.
Bottomline: all Sims are controlled by the AI, including the Sims in favoured relationship with the player.
This results in various ways to play the Sims, that spans from two extremes:
-as many queued input orders as possible.
-as few queued input orders as possible.
The first end of the spectrum is conventional and suppresses the expression of the AI, letting the player run the show.
The second demands that the player takes time to understand what the Sims are.
The first end of the spectrum is about letting the player achieve what the player want to achieve in the game, Sims are mere tools to allow the player to achieve. They are puppets.
The second end of the spectrum is about letting the sims achieve what they want to achieve in the game (virtuality), the player is here to guide Sims throughout their life, pushing a few capital decisions once in a while.
The Sims each have a personality. That personality is not sumed up to the dominant traits. Actually, sims personality is a bit of every trait.
Sims' personality could be represented on a the classical circle with polar opposites to provide an overall vision.
The game does not provide that tool though but through observation or some other tests, it is possible to understand a Sims' personality.
Example: all Sims are, to various levels, brave or coward. Choosing brave/coward as a main traits for a Sims means that they are on the higher end for each. Sims though as secondary traits, might be less or more brave/coward.
It goes the same for every other traits like like the outdoors/dislike the outdoors.
Observation is required to delineate a Sim personality. It is very easy. For example, Sims that has an inappropriate tendency usually walk around in night wear while sims with an appropriate tendency usually dress properly and even choose appropriate dressing.
Same goes for relation to nakedness as sims who do not like to go naked prefer to dress in long, covering clothes etc
That was for the Sims' personality.
Determining the Sims'personality is totally irrelevant when queuing as many orders as possible since the player suppresses a Sims personality.
It is crucial in the other end of the spectrum.
Sims get along better with Sims based on proximity of personality but not only. How?
It is simple because Sims might have a different relationship to their environment, even though when their personality is close.
For example: Sims might have a tendency to like activities involving logics. Satisfying that taste though go through different activities.
For example, one logical Sim might like to play Chess while another might like to use a telescope (it is obviously connected to the outdoor/indoor thing)
Pairing two Sims with one tendency is not enough, they must share the same way to satisfy their tendency.
All these points are vital for players who want to guide Sims through their life, letting the Sims be controlled by the AI most of the time.