[Regulus Black]

Regulus was only sixteen when he joined Voldemort. His parents were very proud of their youngest son, and the young man's happiness knew no bounds! One day, a year later, Regulus offered Kreacher to the Dark Lord because the Dark Lord needed a house-elf to hide his Horcrux in the cave containing the cursed potion.
Kreacher nearly died during his time with Voldemort, and upon returning to Regulus, he told his master everything. After this, Regulus began to consider abandoning Lord Voldemort, betraying him.

Some time later, he asked Kreacher to show him the place where he and Voldemort had gone. In the cave, Regulus pulled a locket (resembling the one Voldemort had) from his pocket. He told Kreacher to take it, and when the cup was empty, to switch lockets and escape alone. After Regulus drank all the liquid and, tormented by an unquenchable thirst from the cursed potion, was forced to drink from the lake, he was pulled underwater by cursed mermaids, intending to drown him. They tugged at Regulus's arms and legs, pulling him deeper and deeper into the water. Regulus felt water enter his lungs and begin to choke.