other spellings Thearon[=most common spelling] Thaeron[=officially correct spelling] Thereon
The eldest and most Loyal Son of Kaizen Rhoisoh, Thaeron is a half-brother to Jonathan and Darcy, having the same father but not the same mother. his mother was Rhoisohan. He might not be the first born but he's at least a couple of hundred years old. He was born on Rhoisoh before the exodus to Moonlight Oasis , and did not go into hiding when his father pretended to be dead. Being a shape shifter he could easily travel disguised as someone else. He can even mimic their genetics in the transport codes in the same way Sen'tran hides jason and Jonathan and Desmond's Genetics.
Thearon is a shape shifter with psychic power and he therefor has no dreaming ability [shifter/telepaths usually can't have dream skills. Therefor it is probably his dream skills which prevented Jonathan from developing shifting skills]
He thinks he ought to be Paragan in the reunited Empire because his father was [he believes unfairly] excommunicated from the Paragan line. By Sen'tran. He is in a sense genetically more Paragan than Desmond Harris .
His basic form is a wildcat, so the battle with him in the form of a wildcat evokes Jason's other battle to protect Harris from the wildcat, and Jason seeing Harris as a wildcat when they first meet foreshadow that.
From shortly after the time Alexandreil was born, he was on ESM controlling Kar'Loh. After Alexandreil is Dreambound in Jason's time, Kar'loh frees himself from Thaeron. THis greatly reduces Thaeron's power and makes him a bit more desperate, leading to his direct attack on Jason and Harris.