Soos in Wikipedia
Soos (ancient Greek: Σόος) was a partially mythological king of Sparta. According to Pausanias Son of Procles, father of Eurypon . His name means stability a key concept for Spartan identity - such personifications of concepts are typical of orally transmitted lists. During his rule Spartans took away freedom of Helots, and took to themselves some territories of Arcadia.
Plutarch wrote that once Clitorians encircled Spartans, preventing their access to water sources. Soos made an agreement that he would return lands if they would be allowed access to water. Then he promised the kingdom to the soldier who would not drink. Every one of them drank except Soos himself, so he refused to keep the agreement..