What is next in the series ?

FD, HE, KF, PG,

The series consists of two distinct alphabetical patterns for the first and second letters of each pair:

• First Letter Pattern: F, H, K, P, ...
  • F (6^th) to H (8^th): +2
  • H (8^th) to K (11^th): +3
  • K (11^th) to P (16^th): +5
  • The differences between the letters are 2, 3, and 5. This sequence of differences follows a pattern where the increment added to the difference increases by 1 each time (+1, +2, +3).
  • The next difference should be 5 + 3 = 8.
  • P (16^th) + 8 = 24^th letter, which is X.
• Second Letter Pattern: D, E, F, G, ...
  • These are consecutive letters: D (4^th), E (5^th), F (6^th), G (7^th).
  • The next letter in the sequence is H (8^th).

Combining both patterns, the next term in the series is XH.