Sarah Michelle Gellar played Michelle Trachtenberg’s older sister on Buffy the Vampire Slayer for seven seasons, and their bond was real.

Gellar, 47, shared a tribute post on Instagram to honor the death of her Buffy co-star on Thursday, February 28. She posted a set of photos of the two in what looks like the making of the supernatural show with an emotional message in the caption that read, “Michelle, listen to me. Listen. I love you. I will always love you. The hardest thing in this world is to live in it. I will be brave. I will live… for you” 💔💔💔🗝.”

More from Spin:

Fans of the Cruel Intentions actress took to the comments section of the tribute post to share their condolences and wished Gellar well.

“Rest in peace, sweet Michelle. I’m going to watch Buffy the Vampire Slayer in your memory. Gone way too soon. 🙏🏿🕊,” wrote one fan of the show, while another noted, “She loved you!! She said in an interview 😢❤.” 

A third fan wrote, “We all know how much you loved her. I’m so sorry for your loss. Sending you love, rest in peace, Michelle. 🕊🤍.”

Trachtenberg’s body was reportedly discovered inside her New York City apartment on Wednesday, February 26, by the New York City Police Department after they responded to a 911 call at her address. She passed away at the age of 39.

To see our running list of the top 100 greatest rock stars of all time, click here.