 This tension was only resolved by Cleomenes' death (or murder) and accession of Leonidas I (Cleomenes' half-brother and son-in-law).Looking forward to Cleomenes' death, his only surviving child Gorgo became his sole heiress.She was apparently already married by 490 to her half-uncle Leonidas I.King Leonidas and Queen Gorgo would have at least one child, a son, Pleistarchus, co-King of Sparta from 480 BC to his death in 459 BC/458 BC.