These two are pretty funny. Fujin only says one word sentences, and Raijin ends everything with "ya know?". Plus, Fujin is always kicking Raijin in the shins every five seconds.
[The Truth]
Yes, there actually is a secret about them!!
Fujin doesn't have some strange disease that makes her talk weird. In fact, at one later point in the game (disc 3 or 4) she actually talks normal!