A clever and intelligent Olesian outcast to the prison island on Olesia. He was accused of killing one man, but as he insists, it was a case of mistaken identity. It is possible that he is telling the truth, since many prisoners are on the island for menial charges.
Eldon is a genius in many respects, but some would consider him to be mentally unbalanced. He was largely responsible for developing explosives from the volatile ores found on the island. He chose the materials, helped calculate trajectories and developed the ignition mechanisms and fuses. But most of his efforts went into fashioning the explosive shots.
Torrell assigned Eldon to help Rodney McKay repair the Puddle Jumper the prisoners shot out of the sky. He eventually decided to switch allegiances and used a knife from the Jumper's supply kits to untie Ronon Dex, who at first had wished to kill him. Eldon made it on foot with the others to witness a Wraith Dart emerge from the Stargate.
Eventually McKay managed to get the Jumper's power systems back on-line to severely damage a Wraith cruiser that had arrived. After Colonel Sheppard ordered Dr. Weir's recently-arrived Puddle Jumper to dial one of the new Alpha Sites (so the prisoners had a place to escape to), Eldon returned with the team to Atlantis, before Olesia was overrun by the Wraith.
Condemned - Dr. McKay meets Eldon, the genius behind the primitive weapons possessed by the Olesian prisoners, and eventually is enlisted to help the team get off the planet.