Michael Bluth is the second oldest Bluth son, but the most competent one.  When George Sr. went to jail, it was Michael who was stuck running Bluth Company and keeping the family together.  Michael's wife, Tracey, died of ovarian cancer two years prior to the first episode and left him to raise George Michael on his own.

Michael Bluth Quotes

You stay on top of her, buddy ... Do not be afraid to ride her ... Hard.
(George Michael looks petrified)

</i> Michael

Gob: Dad's gonna be crushed!
George Michael: You don't have to tell him!

Arrested Development Quotes

Okay, we are just about ass-to-ankles back here, Maeby. Do you want to hop on your cousin's lap there, please?

Tobias

Maeby: Do you guys know where I can get one of those gold necklaces with a "T" on it?
Michael: That's a cross.
Maeby: Across from where?