Oliver searches through his pack and recovers a some twine and a bell. He disappears outside and, after a brief search, carries in some twigs and saplings. He groans, one hand darting to the small of his back, as he struggles into a cross-legged pose onto the floor.
He ties one end of a length of twine to a rock with a sliding knot that barely holds it in place. Hands moving swiftly he ties the other end to one of the greener switches with a knot that will slip if given a good tug. He tests the assembly - it looks like he's fishing with a rock for bait - the rock slips of the end at the slightest touch and the end of the switch lashes back, like a catapult. He tests again, getting Fendric to hold the switch and tugs the string tied to the lash, it gives and the sapling whistles as it rebounds in Fendric's hands.
He nods and ties a bell to the end of the switch and hunkering down, grunting, onto the floor near the hole searching for a crevice, whistling a merry tune and eyeballing the distance to the hole. With a considering look and a swift hand he trims the end of the sapling and wedges the stick into the floor and tests the length. With a satisfied murmur he turns to gather up the twigs and starts when he finds himself nose to nose with a twig-laden Orbril.
"Ach! Pelor's pantaloons!" He glowers and snatches the twigs from Orbril, muttering, "Thanks." He pauses, squinting, "You know, Winkle could use a bite. To eat." He tosses his head at the owlet warbling in its basket. He turns back to his work grumbling under his breath. And I could use some space.
He carefully measures the twigs as he lays them delicately across the mouth of the hole in such a way that if they are disturbed the whole assemblage will fall, loosing the rock and freeing the sapling switch to lash about, ringing the bell. He leaves a space in the middle of the twigs and gingerly reties the rock before lowering it down into the hole and covering the hole with twigs. He stands, dusting his hands, and stoops to gather the remaining twigs and twine and other bits.
"Well, that's it. It's not the most sophisticated. But it'll let us know if anything is creeping outta there."
He purses his lips looking at the contraption and picks a spot near the fire and Bastrop and Winkle. He carefully lays out his armor and puts his shortswords under the rolled-up cloak that serves as his pillow. His crossbow is in easy reach and bolts near to hand.
Been a long time since I had to sleep with one eye open.
He thinks longingly of Raven's flask of brandy and swallows a few mouthfuls of stale, cool water. He takes his meager dinner and stows his gear neatly.
Definitely too old for this.
He settles down and rolls onto his back staring up at the cave roof and the shifting shadows thrown by the little crackling fire. "Goodnight all." After a while he rolls onto his side, back facing the cave entrance, eyes peering into the darkness of the back of the cave. He growls as he tugs on troublesome blankets. In the dim light he can just make out the gleam of the firelight on the bell.
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When shaken to start his watch he wakes with a start, wisps of dreams of his vanished life draining from him. He sighs and rolls back onto his side, eyes closing briefly, before he struggles onto his knees and begins to don his armor in the dim light within the cave.