They've exchange some cute words on Instagram in the very recent past.
It's obvious they're fans of each other.
The pair first met a year ago when Grande was hosting SNL, at the time, both of them were in relationships (Davidson was dating Larry David's daughter Cazzie and Grande was dating the rapper Mac Miller). Based on the recent social media activity, it's obvious the two kept in touch.
Grande recently posted a photo of Davidson on her Instagram story, which is basically the 2018 version of skywriting "I love this fool."
Now that you have all the necessary social media related context for our two lovebird protagonists, we can get to the dirty Harry Potter-themed comment you clicked for.
On Wednesday, Davidson posted an Instagram photo with Grande confirming all of the whisper network rumors about their dalliance.
As you can see, he's wearing Gryffindor robes while she's firmly team Slytherin.
"The chamber of secrets has been opened," Davidson cleverly captioned the photo.
But what I'm really here for is Grande's overtly sexual Harry Potter-themed response:
The people of the internet have a lot of feelings about the exchange.
From over here, they look like a very happy couple of wizards.