Walsh first appeared on Grey's Anatomy's season 1 finale, when Addison and Derek (Patrick Dempsey) were revealed to be married, even though McDreamy had already begun a relationship with Meredith (Ellen Pompeo).
Throughout much of Walsh's tenure on the show, Addison and Meredith were in a love triangle with Derek, before he chose Meredith and Addison moved to California. (Walsh went on to star on her own, L.A.-based spinoff, Private Practice.)
In an Instagram post on Thursday, Addison appropriately side eyes a photo of Meredith and Derek hugging on the beach.
"Gal u already know how Addie would’ve reacted to this," she captioned the post.
While Addison may not be thrilled to have Mer and Der back together, Walsh was, writing, "Sending so much love from overseas to @EllenPompeo & @PatrickDempsey on their internet-breaking reunion."
Pompeo commented on Walsh's post with crying laughing, 100, and red heart emojis.
Meredith and Derek reunited during Grey's' season 17 premiere. The incredible moment happened at the end of the episode when Meredith, exhausted from her work fighting COVID-19, collapsed. The show then cut to show Meredith standing on a beach and waving to Derek, who died back in 2015, during the 11th season of the show.
Following the epic reunion, Dempsey gushed to Ellen DeGeneres about the response to his surprise return.
"The impact, the response, has been incredibly overwhelming and very moving. It was nice to be able to have it work out this way," he said. "There's so many souls that we have lost right now. The thought of having angels around us is very comforting, certainly to me."
Grey's Anatomy airs Thursdays at 9 p.m. ET/PT on ABC.