CASTLE - "Watershed" - In the Season Finale, an interview with a high-profile federal law enforcement agency forces Beckett to reconsider what she wants out of her job -- and out of her relationship with Castle. Meanwhile, the body of a young woman is found floating inside the water tank of a skid row flop house, but as the team investigate, they discover that her final resting place is just one of many strange things about her death, on "Castle," MONDAY, MAY 13 (10:01-11:00 p.m., ET) on the ABC Television Network. (ABC/Richard Cartwright)STANA KATIC, NATHAN FILLION"Castle" crumbled from a pretty lofty height in its last season, and even star Nathan Fillion is willing to admit the ending was not ideal.

Season 8 was the final season, but that was not known as they approached the end of filming. Instead, fans were shocked when it was announced that star Stana Katic was let go and would not be returning for Season 9, which implied that there would be a Season 9 at all and it would somehow exist without Beckett. Then ABC decided to cancel the series altogether, which was a surprise to the remaining cast/producers and led to a rather hurried conclusion including a (tacked-on) time jump into the future with happy Castle and Beckett and their kids.

Fillion talked to the New York Post to tease his new arc on "Modern Family," and shared a pragmatic take on the end of "Castle":

"It wasn't the beautiful send-off that I think maybe you could hope for, but it's the entertainment industry, it's a business, I get it. I don't take it personally when a show gets canceled — I can't take it personally, all my shows gets canceled! Look at my resume, it's a long list of canceled TV shows. The fact is, I made a lot of great friends on a really great show. I'm really happy for everything that that show has done for me."

Over the summer, TVLine had asked Fillion if it was bittersweet to have the show end without a proper send-off? Here's his reply:

"What is a proper send-off? We had eight years of a phenomenal television show with amazing people that I love so very, very much. I'll miss them dearly, I'll miss the characters they play. But at the same time it's been eight years since I haven't had a plan."

When asked where Season 9 would've gone, Fillion confirmed "they were talking about a time jump," but added that "they" (writers, producers) were saving most of their plans for when the show got a pickup and it never got a pickup.

So now he's focusing on his "Modern Family" stint as weatherman Rainer Shine, plus upcoming role in "Guardians of the Galaxy Vol. 2" and voice work in "Henchman" and "Yamasong: March of the Hollows."

"It's kind of a niche for me to play characters who are vain but don't know that they're vain. It's something I'm practiced at," Fillion told the New York Post of his "Modern Family" character. "It's very easy to laugh at a character who's that stupid. He's kind, he's nice, he's sort of charming, but he's just so cheesy and so flawed."

"Modern Family" airs Wednesdays at 9 p.m. on ABC (except for October 19, because of the third presidential debate).

Want more stuff like this? Like us on Facebook.