People watch a TV screen broadcasting a news report on the assassination of Kim Jong Nam, the older half brother of the North Korean leader Kim Jong Un, at a railway station in Seoul, South Korea, Feb. 14, 2017. Reuters

Kim Jong Nam, the brother of North Korea leader Kim Jong Un, died suddenly Monday while traveling through Kuala Lumpur International Airport in Malaysia. It was not immediately known whether he died of natural causes or if he was killed. He was traveling to Macau, China, when he was reportedly attacked.

The Royal Malaysia Police said he died en route to a hospital after seeking medical help at the airport, the New York Times reported. “A post-mortem examination request has been made to ascertain the cause of death,” the statement said.

Not up to date on your Kim Jong Un drama? Here's everything you need to know about his deceased older brother.

1. Kim Jong Nam was Kim Jong Un's half brother.

2. He told officials just before his death that someone had grabbed his face from behind and then he felt dizzy.

3. His age is unknown but he was believed to be in his 40s.

4. He was traveling with a passport with the name Kim Chol.

5. He was considered Kim Jong Il's favorite son before his brother took power.

6. He is believed to have fallen out of favor in North Korea because of his antics, such as visiting Tokyo Disneyland with a forged document in 2001.

7. He didn't attend his father's funeral in 2011.

8. He is believed to have been banished from North Korea.

9. He spent time living in China in recent years.

10. He was overweight, like his younger brother.

11. He wanted North Korea to stop embracing isolation and join the global economy.

12. Under North Korean traditions, potential heirs must be raised separately, so the two brothers never met.

13. His mother was Song Hye Rim, a North Korean actress.

14. He allegedly wasn't interested in power. "Personally, I am against third-generation succession," he told Japan's Asahi TV in 2010. "I hope my younger brother will do his best for the sake of North Koreans' prosperous lives."