Tracks
It didn't take long before Tom stood up and wordlessly began to follow the trail of blood. Reg and Malfoy followed him as he went.
The blood was pooled in the grass where Tom had found her. He cast a quiet Vestigium and the blood began to glow, and despite the grass, the trail began to glow as well. Tom vanished the blood behind him as he followed the trial.
It led to the Black Lake, and Tom felt something inside him go cold when he saw the puddle of blood that was on the banks of the lake, the water was lapping at edges of the puddle. The blood wasn't washing away- it had coagulated. Tendrils of blood, that looked like arteries, were swaying gently with the swaying water. Tom crouched and dipped a finger into the puddle, Malfoy looked away, but Tom's finger came away without any blood.
Tom conjured a large flask, pointed his wand at the blood, whispered Conjugo. The puddle rose like a viscous mesh, with small cracking sounds as it came away from the earth and Malfoy turned his back again. Tom whispered Solvo, the blood lost the viscosity it had gained in the sun and the earth and flowed freely into the flask.
Where the puddle had been, Tom saw a small bag, the kind that Malfoy stored his diamonds in. He summoned it, stoppered the flask, shrunk both the blood and the bag, cast an unbreakable charm on the flask and then stored them both in his pockets.
Then he stood there, looking out at the Black Lake. The willows around them gestured gently with the flowing wind, the water was dark but calm, and lapped gently at his feet.
Malfoy and Reg too were quiet and Tom didn't know how long he stood there, but it was Malfoy's grumbling that finally made him realize they were missing a Sunday lunch.
He followed Reg and Malfoy, looking back once from the edge of the trees, to where the pool of blood had lain, drying in the sun, seeping into the earth and being washed away by the water.