It started with a letter and ended with a bombshell.
Justin Chambers, who plays Dr. Alex Karev in the long-running ABC medical drama "Grey's Anatomy," left the series after 16 seasons with Thursday's episode.
He had been with the show since the 2005 pilot.
While fans of the series anxiously awaited Dr. Karev's fate since January, when Chambers announced his departure, a tentative answer came in the episode's first five minutes.
In a letter, Alex revealed that he will not be returning to Seattle -- because he is with his ex-wife Izzie, a character played by Katherine Heigl, who exited the series in 2010.
Alex explained he reconnected with Izzie during the fight to reinstate Meredith Grey's (Ellen Pompeo) medical license. He then revealed he is a father of Izzie's 5-year-old twins.
To explain how that happened, Izzie decided during the fifth season of "Grey's Anatomy" to have her eggs frozen when she was diagnosed with cancer, as they would not survive the treatment. But to give them a better chance at being viable later, Alex fertilized them.
Upon his separation with Izzie, Alex signed papers giving her complete control of the embryos -- so she decided to have his children without letting him know, as she had no legal obligation anymore.
When he met his children in secret earlier this season, Alex immediately fell in love with little Alexis and Eli and decided to give them what he never had: a stable family with a loving mother and father.
So, while Alex has his happy ending, those within the walls of Grey Sloan Memorial Hospital are left reeling.
Jo (Camilla Luddington) was served divorce papers leaving her all of Alex's possessions, Dr. Bailey (Chandra Wilson) and Dr. Webber (James Pickens Jr.) lost their most tenacious student, and Meredith found out that she is her own person.