FN-2187 was simply Eight-Seven whenever one of the team wanted to shorten his designation. They didn’t do it very often. He was, as far as the training cadre and his peers were concerned, one of the best stormtroopers anyone had ever seen. He was everything their instructors wanted—loyal, dutiful, brave, smart, and strong. Whatever the test, whatever the evaluation, FN-2187 consistently scored in the top 1 percent. So he was FN-2187, well on his way to becoming the ideal First Order stormtrooper.
That was what everyone thought, at least.

Before the Awakening - Finn