Frisk is following a siren song. 

It comes and goes.  Most days she feels it thinly through the gloom, a not-sound she unspools like a thread as she goes.  Other days — today — it’s so strong that it’s nearly a hunger.  Frisk feels it like a sun behind her eyes when she turns along the moss-choked paths, like a living thing tangled up in her ribs. 

Days like that, there’s nowhere else to go but down. 

---

The creatures in the dungeons mostly ignore her, as long as she ignores them. 

She flattens her ears and kicks away an encroaching slime, shaking away the clinging ooze on her hoof.  She spooks a family of living mushrooms with bared teeth.  But she’s concentrating on the dungeon itself.  Her mouth is sweet with the taste of it, today.  She can almost see something in the dark ahead of her, an almost-familiar shape. 

It takes Frisk several turns to realize she’s being followed.  A soft click of hooves like an echo of her own, tailing her as she goes.

She turns sharply, teeth bared, ears back. 

The courser shies away from her.  The satisfaction of their reflexive fear nearly snuffs out the sweetness. 

“What do you want?”

“There’s — up ahead.  There’s a cavern of bats.” 

“So what?  I have to go that way.”  The wanting drags at her.  Forward, downward, deeper.  It would take her through stone if it could.  Through earth. 

The courser’s eyes shine red, even in the shadow.  They take a step towards her. 

“It ends better if you aren’t alone.” 

---

They stand at the mouth of the next corridor, looking up, although Frisk can hear them better than she can see them.  The susurration of many small bodies, soft sleep sounds, shifting among the vines.  Fur and leathery wing.  The occasional glint of a bright, shining eye. 

“What happens if I’m alone?” she asks. 

“Oh.  I don’t know.”

Her ears flick, annoyed.  “What?”

“I’m just supposed to be with you.  I saw it.  They don’t hurt us as long as I’m with you.” 

Frisk looks up at them — hundreds of them, huddled, chirping and shy.  She imagines the press of fangs through her hide, death by a thousand bites.  The weight of them, the first one almost infinitesimally small, but the fiftieth — the thousandth tiny body, dragging her down—

Beyond the cavern, the darkness pulses like a heartbeat.  The soundless hum of it feels like the movement of ancient stone, all the way down to her bone. 

She wants—

She has to.

 ---

“Okay,” Frisk tells the courser.  “Keep up, then.” 

She steps into the cavern, listening to the whisper of wings overhead, and Prosper follows.