  We present a framework for understanding the recently observed cascade
transitions and the Landau level degeneracies at every integer filling of
twisted bilayer graphene. The Coulomb interaction projected onto narrow bands
causes the charged excitations at an integer filling to disperse, forming new
bands. If the excitation moves the filling away from the charge neutrality
point, then it has a band minimum at the moire Brillouin zone center with a
small mass that compares well with the experiment; if towards the charge
neutrality point, then it has a much larger mass and a higher degeneracy. At a
non-zero density away from an integer filling the excitations interact. The
system on the small mass side has a large bandwidth and forms a Fermi liquid.
On the large mass side the bandwidth is narrow, the compressibility is negative
and the Fermi liquid is likely unstable. This explains the observed sawtooth
features in compressibility, the Landau fans pointing away from charge
neutrality as well as their degeneracies. By providing a description of the
charge itineracy in the normal state this framework sets the stage for
superconductivity at lower temperatures.
