It’s not a crossover. Ted is not leaving Robin to get together with Meredith Grey. But the How I Met Your Mother actor’s arch on Grey’s Anatomy has fans reeling.

Josh Radnor, who played Ted Mosby on the CBS comedy, is traveling to ABC to join the Shonda Rhimes drama. In a sneak peek shown by PEOPLE , we can see Meredith getting ready for a blind date. She apparently knows nothing about the guy since her matchmaker doesn’t want her to have any expectations. Fans, however, have been clued into who the mystery man is.

Given Radnor’s track record with women on television, fans are a bit wary. The slightly annoying Ted was known to be a hopeless romantic who had us guessing for almost 10 years who the mother in question was. Finally, the big revelation led to a controversial ending for the show, when the supposed love of his life died, leaving him to get back together with Robin, the Canadian girl we were all rooting for all along.

One fan, well of aware of Radnor/Mosby’s history, warned the actor. "You break her heart, I’ll break your neck @JoshRadnor," zac_patty3 wrote. The actor soon replied, saying, "Terrified to let you all know I'll be on Grey's Anatomy tonight." Watch your back Radnor.

Radnor joined the show for its fourth episode of the season, which aired on October 11. It’s not clear how long the actor will be around for. ABC announced, that the episode was a two-hour crossover event with Station 19, a spin-off of Grey’s, which follows a group of firefighters of the Seattle Fire Department. Radnor, however, is not on Station 19, so how it fits into the crossover is also a mystery.

On Thursday’s episode the blind date did not go well after Radnor’s character, John, made a comment about single mothers, which irked Meredith, a widowed mother of three. According to Ellen Pompeo, aka Meredith Grey, the show is looking for a partner for her character but will apparently send her on numerous dates.

"Meredith is gonna date, date, date, date, date, just like my friends who are ready to jump back into the dating world do. What does dating look like today? I think we're almost phasing out the dating apps now. I'm hearing like people are not liking the dating apps anymore. I don't know, I'm just really happy I'm not single in real life. I try to listen to everybody's stories, all my friends and even people that I don't like that much, so we can tell a story that resonates true with people who have been through something like this," Pompeo said.

RELATED: Grey's Anatomy: 20 Questions Fans Still Have About The Show

Just as well since many fans are not too keen on Radnor. On Twitter, Sarah Sahagian wrote, "Josh Radnor? But he's just Bizarro Universe Dr. McDreamy! I mean, if you squint real hard, he looks JUST LIKE Patrick Dempsey! #GreysAnatomy." Don’t bother trying. He doesn’t.

Tips To Grow Your Hair Faster, According To The Experts
Tips To Grow Your Hair Faster, According To The Experts
About The Author