He is lanky. He has a round face.
Jonneth was found in the Two Rivers by Mazrim Taim and brought to the Black Tower. He is one of the most skilled of the Two Rivers Soldiers. He, along with Algarin Pendaloan (Emarin), Canler, and Arlen Nalaam are leveling hillside with the One Power. Alongside them is a group of Taim's men led by Coteren.
Coteren mocks Androl Genhald who has stopped by and embarrasses him in front of everyone by showing how weak he is in the One Power. Jonneth's group become furious and everyone fills with saidin, just about leading to open battle between the two groups before Androl manages to calm them all down by making light of the situation. After Taim's group leaves, Androl agrees that they will start to investigate the bizarre changes that are happening to people.
Some time after he still has not been raised by Taim, despite being as strong and skilled as any Dedicated. When Welyn returns to claim Logain and Taim have patched up their differences, he is openly doubtful and questions Welyn on it. He only stops when Lind Taglien distracts him.
After the Black Tower was freed from the Shadow, Logain promises to raise Jonneth to full Asha'man; he stays at the Black Tower with his friends even though he could be claimed by an Aes Sedai.
Before the Last Battle starts it can be supposed that Jonneth is raised as a full Asha'man.
During the Last Battle Theodrin starts following him around and Heals him after they escape Demandred. She seems very fond of him and Pevara tells to Androl that for her Theodrin wants to bond Jonneth as Warder.
He disguises himself as a non descript Darkfriend when they go to try and steal back the Seals.