This is a delicate part, of the assembly ear+head.
Select the faces as above and erase them.
Merge the ear in the scene with the head. Adjust the scale and direction (in general a light rotation on X and another on axis Z for User).
Hide the head.
For right-hand side, (looking into the ear as shown) remove the 2 triangles of the previously extruded parts. Make visible the diagonal edges.
Select the internal edges of the ear and extrude with shift+scale.
To simplify the geometry use Weld Target as in the image above.
Adjust the vertexes to give a round form which is the part of the ear that will connect to the head.
Put the vertexes approximately on the same plan.
See the countours of the face, and the dimentions of the ear after adjustment of the vertexes.
Align the ear compared to cranium.
Select the ear and view its Properties (right click) and Trun off BackFaces Culling. That makes it possible to see the faces whose normals are not directed towards the observer.
Select the head, activate 3d Snap in vertex mode and with Create Vertex, create the vertexes for the head in the same arrangement as the ear ones (as shown)
With the new vertices ready in the head you can now hide the ear as these are enough to build the faces that form the of junction of the head to the ear. As usual, make as many quads as you can.
Adjust the vertexes around the edge to give a more regular form.
Place the ear so to allign the pairs of vertices on head/ear as close as possible.
Select the head and then Attach. (check that you have Editable Mesh in the pile of both objects, if necessary, remove a Meshsmooth and colapse the stack).
Select the vertexes pairs and then weld them together.
The ear and the head should now be one with no gaps or holes in this area.
Make any final adjustments of these welded verticies to harmonize the curves of the ear-head join.
The look of the final low poly cage.
It is this low polygon mesh that you preserves for the next parts.
Subdivision in iteration 2.
The next part will be devoted to the modeling of the accessories (clothes, sword, but also the hair and eyes).