Laerta
She's got the humor of a clown, the brain of a genius, and the patience of a saint. She'll help you, but she'll also tell you when you're being a total idiot.
She laughed so hard at my friend's dumb joke that she fell off the chair.
She explained calculus to me in five minutes and I still didn't get it.
She told me to stop being a total mess and just do my homework.