She finished off the caption by confessing: "… and then we drank each other's blood."
Fox, 34, and Kelly, 30 (real name Colson Baker) began dating after meeting on the set of their indie thriller, Midnight In The Switchgrass in early 2020, shortly after the actress split from her husband of seven years, Brian Austin Green.
The couple has been very public with their romance since they got together, regularly sharing PDAs on the red carpet at events.
In an interview in July 2020, Fox claimed she knew before she'd even met Kelly that "some wild sh*t" was going to happen once their paths crossed.
Speaking on the Give Them Lala … with Randall podcast, Fox said she could sense something was going to happen between the two of them when she was told they'd both been cast in the movie Midnight In The Switchgrass.
"I could feel that some wild sh*t was going to happen to me from that meeting (about the film where she found out Kelly had been cast), but I wasn't yet sure what," Fox said.
"I just felt it like, deep in my solar plexus, that something was going to come from that, so then, we met on set."
Fox went on to say that as soon as she met Machine Gun Kelly, she knew "he was what I call a twin flame".
"Instead of a soulmate, a twin flame is actually where a soul has like ascended into a high enough level that it can be split into two different bodies at the same time," she said. "So we're actually two halves of the same soul, I think. And I said that to him almost immediately, because I felt it right away."
On the second day of filming, Fox invited Machine Gun Kelly to her trailer so she could read his astrology charts.
"I went deep right away," she said. "I knew before I even did his chart, I said to him, he has a Pisces moon. I could tell by his energy."
