Sieple was born and raised in Chicago, where he spent most of his life. He spent his last years in San Francisco, where he relocated in the early 1990s.

Sieple was an early leader of ACT UP/Chicago, participating in actions throughout Chicago with Danny Sotomayor, Tim Miller and others who protested the government's silence as AIDS ravaged Chicago's gay community.

"His life was short and voluminous," remembered Bob Huffman, Sieple's former partner from his ACT UP days. "He was a charmer, had a wonderful engaging personality."

Sieple held a number of jobs over the years. He never attended his college, but his impatience drove him to pursue career after career. According to Huffman, he excelled in everything he tried.

He worked as a model, a go-go dancer, a flight attendant, a real estate agent and a travel agent when he was younger. In his later years, he worked as a deputy sheriff in San Francisco. Most recently, he managed property.

"He really had a thirst for knowledge," said Huffman. "He was really inquisitive."

Sieple was born in 1960 in the Chicago area and grew up in Glen Ellyn. His childhood was not easy, said John Ferrel, a friend from San Francisco.

"He took quite a few beatings for being gay," Ferrel said. "That prejudice and those beatings that he took were sort of fuel for the fire that made him more compassionate."

He came out at a young age, Ferrel said, despite the cost of discrimination he faced.

In 1982, a young Sieple found out he was HIV-positive. He fought desperately to stay alive as the virus was decimating his community. He used his job as a flight attendant to travel the world, testing out treatments from Mexico and other countries as they became available.

In August 1987, Sieple attended his first meeting of Chicago for AIDS Rights, a group that would eventually become ACT UP Chicago. It was also the first meeting of AIDS activist Tim Miller, who befriended Sieple at that time.

"All of those people were running as fast as they could to try to stay alive," Miller said.

Sieple was with ACT UP/Chicago at its start and worked on treatment issues, speaking passionately about drug protocol and participating in actions throughout the city. He was arrested multiple times for protests and participated in the organization's largest demonstrations.

He was motivated in part by desperation, said Miller. Sieple was determined to live, and he did so against the odds for decades after his diagnoses.

In the early 1990s, he moved to San Francisco with his partner at the time, Joshua Margulies.

His activism remained strong, said friends. He coached many through substance abuse recovery as a sponsor.

With Margulies, he raised twin sons—Adam and Noah, who are now 8.

"He was an incredibly devoted father," said Ferrel. "He was a great example to me of how to live life to the fullest."

Ferrel remembers Sieple standing with his sons outside of GLIDE Memorial Church one day as people receiving social services exited the building. Sieple and his sons, 5 years old at the time, were handing out peanut-butter-and-jelly sandwiches.

Margulies and Sieple eventually separated. Friends say Sieple remained a devoted father.

On Jan. 5, Sieple was home with friends in San Francisco when he complained that he was not feeling well. Sieple collapsed and passed away shortly after.

Sieple is survived by his mother, Florence Sieple, and his brother and sister.

Friends remembered Sieple as an opinionated and impatient person, eager to change the injustices around him but fun-loving all the same.

His activism continued quietly beyond his involvement with organizations, said friends.

"He always had someone that he was caring for with AIDS," said Ferrel.