Image credit: Julie Jacobson/AP Photo

Just as we thought Facebook CEO and newly minted billionaire Mark Zuckerberg was on top of the world, he surprised even his friends by marrying his college sweetheart, 27-year-old Priscilla Chan, just after he led the company to one of the biggest IPOs in tech history.

Zuckerberg has been in the spotlight ever since Facebook went big and his life story was even portrayed on the big screen in the movie, "The Social Network." But who is his new billionaire bride?

The couple met in 2003, long before Zuckerberg made a name for himself with his billion-dollar idea. According to The New Yorker, they were both in line for the bathroom at a party hosted by Zuckerberg's fraternity, Alpha Epsilon Pi.

"He was this nerdy guy who was just a little bit out there," Chan told The New Yorker. "I remember he had these beer glasses that said 'pound include beer dot H.' It's a tag for C++. It's like college humor but with a nerdy, computer-science appeal.'"

Chan, a Chinese-American from Braintree, Mass.,  graduated from Harvard in 2007 with a degree in biology, according to the Daily Beast. Before that, she graduated as valedictorian of Quincy High School in Massachusetts in 2003.

Chan began work at The Harker School, a prestigious San Jose grade school, in the summer of 2007, teaching fourth and fifth grade science classes. She described her role on her Facebook page as "Hanging out with the little ones and trying to explain how the world works."

She left The Harker School in 2008 to attend medical school at the University of California, San Francisco.

She graduated from UCSF on May 14, the same day Zuckerberg turned 28 and just five days before Facebook's blockbuster IPO.

According to Forbes, Zuckerberg attended the graduation ceremony, checking in via Facebook at the Yerba Buena Center for the arts, and wrote, "I'm so proud of you, Dr. Chan :)."

The couple used her graduation party as a decoy for their wedding. According to the Associated Press, 100 guests gathered at the couple's home in Palo Alto, Calif., to celebrate Chan's graduation.

But what they got was a surprise wedding. The couple had been planning the ceremony for months but kept it a secret.

"Everybody was shocked," an anonymous guest told the Associated Press.

Zuckerberg designed the ring, which featured "a very simple ruby," the guest said.

Chan wore a traditional white dress by designer Claire Pettibone. According to People Magazine, the "Sky Between the Branches" gown was "an ivory laser-cut floral dress adorned with matte sequins lined in silk. The gown featured subtle cutouts in the overlay, plus an illusion jewel neckline, sheer back and chapel-length train. The dress retails for $4,700."

Although the ceremony coincided with Facebook going public, the Associated Press states that Zuckerberg and Chan planned the wedding around her graduation, not the IPO.

No word on if the couple signed a prenuptial agreement, but Chan did require they both sign contracts before she moved in with Zuckerberg in 2010, according to The Daily Beast, which said she is fluent in English, Spanish and Cantonese and encouraged Zuckerberg to learn Mandarin.

Chan may have also influenced Facebook's decision to include an option to become an organ donor by signing up on the site. Along with Sheryl Sandberg's dedication to the cause, which she described to ABC News' Diane Sawyer, Zuckerberg also cited his soon-to-be-wife as inspiration for the addition.

"Our dinner conversations are often about Facebook and kids, and the kids that [Priscilla's] meeting," Zuckerberg told ABC News' Robin Roberts. "She'll see them getting sicker, then, all of a sudden, an organ becomes available, and she comes home and her face is all lit up because someone's life is going to be better because of this."

The couple adopted a Hungarian sheepdog they named Beast in 2011. And of course, the pup has his own Facebook page.

Her husband is now worth an estimated $20.3 billion, according to Morningstar IPO analyst Jim Krapfel. But with a medical degree, fluency in three languages and the fact that she met Zuckerberg before Facebook earned him billions, it seems Priscilla Chan is not your average billionaire bride.