Ac load line analysis

The DC Load Line is simple to explain, for a given circuit the relation between V_CE and I_C must comply to the KVL relationship for that circuit.

In the graph we can choose a Q point, and then see if we superimpose an AC signal on top of the DC voltage then the V_C will follow accordingly, and we can determine the maximum output swing.

The AC Load Line confuses me however. Because when I determine this line using the AC equivalent circuit model and KVL across the v_ce loop, the load line now goes through zero on a graph.

i_c = - v_ce / (R_C // R_L)

Then I understand to get the true load line of the circuit, I must superimpose the AC Load line on the Q point, and preferably use the middle of the AC LL as the Q point.

I then get this: