There are many people that make up my sister

There are many people that make up my sister.
Like a person with three arms and no head
Who nods along to rock until night is dead,
They’re sometimes shy, sometimes loud. 
 
Then there’s a thinker, a chooser, a debater,
Who always has the coolest idea,
They’re always here,
Because everybody needs their help
 
Then there’s a fighter, with no eyes and red lips
Who only comes out when the others aren’t there
She goes against the gymnast, who has not a care
Who jumps on other’s heads when they want a laugh.
 
There are many people that make up my sister.
But my favorite must be the mad hatter,
She’s not very big, but that doesn’t matter,
Because she always comes out, and makes me laugh.