I disagree that there is even such a thing as Protestant theory. There is Baptist theology, and Calvinist theology, and Lutheran theology, etc.
That said,
The alone in faith alone is not a statement that says this is all you need. The alone means it is the only way we access justification.
We are saved by GRACE alone. The alone means there is no other way we receive salvation. Salvation is by Grace alone.
Through faith alone in Christ alone. Justification is by faith alone. The alone means there is no other way to access justification. The second alone means simply that it is only through Christ’s passion, death and resurrection that salvation possible at all.
It is all by grace, not by anything we do or have earned.
Now, justification frees us to do the good works He places before us to do. We are bound to obey His commands, not out of fear, but out of joyful thanksgiving for His grace and love of our neighbor.
We can from this point, of course, choose to reject His grace (free will), and turn from saving faith.
Do good works save us? No. Grace saves us.
Are good works (love of our neighbor) necessary? Yes. Why? Because it is the command of our Savior. We can choose to reject His call and live in sin, but we receive salvation through grace.