Sinuous is an adder who appears in the books and the TV series as the mate of Adder. As such, in the books the character is female and in the TV series the character is male. In the books, Sinuous has a very cool relationship with Adder, but they become much closer as the series goes on and they eventually produce offspring. In the TV series, the two adders immediately become very close and are virtually inseparable. Sinuous is killed by the rats in both the books and the TV series.