What Comes Next In The Sequence; AF, BE CF, DI, FD, ??

Substitute the letter with their respective numbers from the table below;

Let see what they give us;

AF = 16

BE = 25

CF = 36

DI = 49

FD = 64

So you see the pattern is actually of square of numbers from 4 to 8, so the next number will be the square of 9 which is 81.

Now representing 81 in terms of letters we get HA

Answer = HA