Imaginary Friend

Imaginary Friends is a feature included in The Sims 3: Generations. The Imaginary Friend is a character that a child creates after a relative sends it as a birthday present right after they are born..

Methods of Obtaining an Imaginary Friend
There are two primary ways to obtaining an imaginary friend. One is to move a family with a toddler into a neighbourhood. There is a chance when you start playing a new family that the toddler(s) will have a doll in their inventory. The second method is to have a baby in-game. There is a 75% chance that, when a new baby is born, a mysterious relative will send the Imaginary Friend Doll in the mail. The doll will immediately appear in the baby's inventory when an adult goes to the mailbox.

When naming the doll, players can set which gender it is by choosing whether its name is a boy's name or a girl's name. If a toddler Sim plays with the doll frequently, it will grow into a child-sized playmate who will happily hop onto the opposite end of a seesaw. An Imaginary Friend may even run minor errands for the child if they have a decent enough social relationship with it.

Simology
Only the Sim that made an Imaginary Friend can see it. For example, if the Sim who made the Imaginary Friend hugs it, and a another Sim sees this interaction, that Sim will think the kid is hugging the air. Interactions with an Imaginary Friend can only be done on the active family's lot. Once the kid leaves the property, the friend becomes a doll in his or her inventory.

Imaginary friends come in a variety of patterns, with either spots, stars, or stripes. There are twelve possible patterns in total. Imaginary friends can act as private helpers, cleaning and fetching for their creator Sim.

Playing with the Imaginary Friend fills up the social motive in the same way as socializing with real people would. Even as children grow into teenagers, they can keep their Imaginary Friends around, and can even develop a romantic interest in their make-believe buddies. If the Sim is good with the Chemistry Set, they can create a potion that will turn their Imaginary Friend into a real Sim. When turned into a real Sim, they will wear unusual clothing that resembles their original appearance. Although they have become "real" Sims, they can switch back to their doll mode at will. Sims cannot WooHoo with Imaginary Friends unless they have been transformed into real Sims and are not in their doll mode.

It is currently unknown if Imaginary Friends can have their own Imaginary Friends, or if Imaginary Friends can even see other Imaginary Friends.

The Sims: Makin' Magic
In The Sims: Makin' Magic, there is a charm used by children that can let them have an Imaginary Friend, although in the Sims, they are called "Invisible Friend", but it is basically the same idea. Invisible Friends in this game look just like normal female child sim. They follow the Sim that created them wherever they go, (except for school). When their creator is at school or is asleep, they will wonder around the lot, and have no needs.

To get an Invisible Friend, the child needs to get 1 Toadstools & 2 Faerie Dust. To get Toadstools, the child needs to sit on many different toadstool stools a lot (they can be aquired with Buy Mode). To get Faerie Dust, the child needs to play with a pink chest (available in Buy Mode).

After the Sim has cast the charm, they can cast it again anytime they want (unless they sell the charm). It has been known that the invisible friend may act badly towards the child sim if the sim is in a bad mood at the time of casting. It has also been known for multiple friends to be cast, but they all look the same. Just like a female child sim.