We LOVE River Song - have you not seen the entire series?
I am 4-5 episodes into the 5th season now. Matt Smith is the Doctor now and Amy his companion.
River Song has been in 2 episodes, the one in the library and the one with the angels where they had to go through the catacombs.
The fact that she seems so familiar with the Doctor and doesn’t treat him with reverance is different. Like she’s his wife, as Amy put it.