Superboy readers in 1964 would have remembered “The Knave from Krypton” from about three years earlier, when he taunted Superboy in Adventure Comics #287 and #288. He’s the juvenile delinquent who lived next door to Jor-El and Lara on Krypton, and who, when his attempts to steal Jor-El’s rocket plans were foiled by baby Kal-El, placed himself and his parents in suspended animation in a lead-coated bomb shelter. They all survived the destruction of Krypton and landed on Earth 15 years later.
What is Dev-Em doing in the 30th Century? Um… we’re never actually told.