Nathan Fillion, a former Castle co-star, shared a request with fans ahead of Season 5's premiere

Nathan Fillion, a former Castle co-star, shared a request with fans ahead of Season 5's premiere ...

The Rookie, an ABC cop procedural, is returning for a long-awaited Fall 2022 TV broadcast season, and the stars have made sure to keep viewers entertained by dropping behind-the-scenes footage and unveiling new, official Season 5 footage. Nathan Fillion asked fans something related to the upcoming season, and he responded in a silly way.

Fillion took to Instagram to request fans to tell him three things they're doing to prepare for the new season. While there were plenty of responses from fans, Castle star Seamus Dever hopped on the train, and its pretty funny:

Hydrating, stretching, and doing deep sea breath training are all part of our deep sea breath training.

Seamus Dever played Detective Kevin Ryan in ABC's mystery crime drama before guesting on The Rookie in a Season 2 episode. He has also portrayed John Seed in the video game Far Cry 5, but he hasn't forgotten his castle roots.

Nathan Fillion has still managed to bring up Castle once in a while, even if it is to applaud the series. There have also been other Castle reunions on The Rookie, so maybe more will be added in the future, especially since Dever commented on Fillion's tweet about the new season.

Shawn Ashmore, fillions The Rookie co-star, expressed his delight at Season 5 by commenting on his tweet, and the emojis mean a lot:

In addition, the official The Rookie account had commented and was already clapping for the season:

The Rookie's fifth season is shaping up to be a great one, and it's not just because Chicago P.D. vet Lisseth Chavez has joined the team. It's also expected to be interesting to see how Tim and Lucy ended the season, as well as when Niecy Nash-Betts joins the expanding universe as the star of her own show.