The long-running medical drama television show by ABC, "Grey's Anatomy," has fans saying goodbye to a major character. Dr. Nathan Riggs, played by Martin Henderson, has left the show just after two seasons of being a regular character in the series. Characters coming and going has happened numerous times on the show, which begs the question: why does this keep happening in the first place?

In a report by E! News Online, there were numerous reasons as to why past characters had been written off. For the likes of Patrick Dempsey who played Derek Shephard, he donned the leading male role for 11 seasons but decided that it was time to move on to other things. This was a similar case with most of the departed cast members, but with Henderson, it was a little bit different.

According to Deadline, fans were caught by surprise regarding Dr. Nathan's departure. The episode was dramatic and riveting, and revolved around Megan Hunt's disappearance in Iraq, played by Abigail Spencer. Dr. Nathan decided then that it was time to start anew in Southern California and attend to Megan's Iraqi son, Farouk, played by Bardia Sieri. This was a rather good ending compared to most of the cast members who had left the show.

Furthermore, Henderson explained that he always knew that his stint at "Grey's Anatomy" would be short-lived. The actor claimed that he does not commit extensively to projects, and that this was an understanding he and the show's creator, Shonda Rhimes, came to before he signed on to play Dr. Nathan. Fans may have grown attached to the character, but the fact is that he could return at any time since he was not written off as dead.

On the bright side, fans will not have to wait too long for the Dr. Nathan-shaped hole in their hearts to be filled. The show's creators have already set their eyes on Bethany Joy Lenz to fill in for him, according to She Knows. For now, she will be a recurring guest filling in for the lack of doctors in the show.

"Grey's Anatomy" airs Thursdays at 8 p.m. EDT on ABC.