Athena reached out and offered Zoe her hand. This wasn't strictly necessary, but she wanted to touch her, so there it was. Zoe, for her part, was excited about the ritual and just as enamored with Athena, so this wasn't an issue.
Athena began to explain what she would try to do. "The purpose of this particular rune is to trace magical residue. There's a couple different spells I want to perform with this, but I'm gonna start with a malice detector. This could confirm foul play, but if it doesn't that means that any side effects," she says, looking Zoe up and down suggestively, eliciting an smirk from her quarry, "are at least unintended."
She flipped open the book to a dark, creased, leathery page and marking an entry with her finger began to recite the spell. The rune, still a shimmering purple, began to pulse with every syllable. As Athena completed the incantation, the area inside the rune began to glow an unearthly green. A thin strand of green light extended from the rune and lit the shadow of Zoe's right index finger where it was projected on the ground to her side.
"Well, looks like the thing's malice free- and that it's your older brother's. So, I guess he didn't get it from a friend or anything."
Zoe breathed a sigh of mock relief. "I'm so glad he's learned not to take penises from strangers." She moved her hand around, watching the glowing shadow.
"You never know Zo- I haven't been at this very long, but I've seen some pretty twisted shit get pulled by angry witches." Athena relented, "Though I must say, boners are by far my medium of choice for spellwork."
"Alright- round two. Let's see where it came from. Some things can be conjured, some transmuted, maybe even spell-crafted. Or it could be completely normal." She looked again into Zoe's eyes. It was still weird, but she really wanted to just go in for a kiss. "Ok, so definitely not normal."
Again she flipped through the book, found an entry, and recited it. The rune dimmed, leaving the room much darker than it had been when basking in it's (very welcome) green confirmation that no malice was involved. Zoe looked sad that her shadow had stopped glowing.
The rune lit again, this time a soft white. "Wait, what the fuck?" Athena looked stunned.
"What? What's wrong with it?" Zoe used this query to lean in close.
"It's... apparently completely normal. And unless I'm very mistaken, this is very mistaken."
They both sat and pondered what this meant. There's no way in hell this thing was natural, and yet... spells don't lie... Athena relayed as much to Zoe.
"Wait. So spells don't lie. But what if it believes something false?" Zoe asked, expecting to hear a reasonable explanation as to what she didn't understand about witchcraft.
Instead, Athena gaped at her. "Oh shit. That's it."
"Really?"
"It has to be! We're dealing with a magic item, but the spell doesn't see it as such. We're dealing with some serious power to hide that much." She gawked at the ghostly glow. "Just who the fuck is your brother?"