c
B (Black). Order of snooker balls.
dadas
The next two letters are likely C & U. There are at least 2 patterns in these letters. FIrst is the list of vowels that make up every other letter. Then the letters alternate from the ends of the alphabet. If there is a Z, a B, then a Y, then C would likely be next, and then X. But there would be whatever vowel in sequence next.
jason
bb
abcde
z
fug
The next three letters in this sequence follow by days of the week. S is sunday, m is monday t is tuesday, w is wednesday, so the next three letters are tfs because thursday friday saturday.
MAMJJASO are the initial letters of the months from March through October, so the next letter in the sequence is N for November.
bb
jj