Young Nox boy, the most curious of the family group of Nox consisting of himself, Ohper, Lya and Anteaus, that lived on the forest floor of the Nox homeworld. Nefreyu took an interest in Samantha Carter. He studied Jack O'Neill and his construction of a bow and arrow, suggesting that the arrow was too sharp to shoot down fruit from the highest branches.
Later, Nefreyu went off and located Apophis and his guards, greeting them in peace -- and Apophis killed him. Nefreyu was revived by the Nox in their life ritual, and eventually saw SG-1 off at the Stargate with Anteaus.
The Nox - Nefreyu is one of the few Nox who first reacts positively to the presence of SG-1.