The Character component is simply a utility component that can optionally be attached to an actor gameobject and is only required by some very specific ActionClips, like Character Look At and Character Expression, which are specialized for humanoid characters. The Character component simply helps you into managing some of the properties used in these ActionClips, so that whenever and wherever these ActionClips are used, the settings remain globalized around the actual character.
There are two sections and functionalities related to the Character Component, those being the character Look At transforms and the character Expressions list.
The first two transform parameters, Neck and Head, are related to the Character Look At ActionClip, which is a very easy way to make the character look at a target location or object.
The second part, Expressions, is where you can create your character expressions out of using it’s BlendShapes and is related to the Character Expression ActionClip, which actually makes use of the settings set here to animate the character’s expression.
Each Expression is defined by a number of different blend shapes and weights, chosen among any of the character’s SkinnedMeshRenderers within it’s whole hierarchy and of course a name for the expression itself as a whole, e.g. “Happy”.
You can also preview the expression while creating it in this inspector, by setting the expression’s total weight to a desired value above 0.
You can have as many expressions and as many blend shape targets within an expression as you wish.