Who is…
Aretas

also known as: Aretas IV Philopatris

He is the father-in-law of Herod Antipas, and king of Arabia Petraea/Nabatea. He was King of the Nabataeans from about 9 BC to 40 AD. His wife was Queen Huldu.

His daughter princess Phasaelis (aka Pasiel or Phasael) returned to him when her husband committed adultery with Herodias, the wife of Herod Philip 1, his half-brother (Luke 3:19-20; Matthew 14:3).

For Herod himself had sent and had John arrested and bound in prison on account of Herodias, the wife of his brother Philip, because he had married her. —Mark 6:17

This led to a war between Aretas and Herod Antipas. Herod’s army was completely destroyed (36 AD).

Aretas, taking advantage of the complications created by the death of the Emperor Tiberius (37 AD), took possession of Damascus (2 Corinthians 11:32; compare Acts 9:25).

At this time, the Apostle Paul returned to Damascus from Arabia.