Regulus had known exactly what he was walking into. Kreacher had been nothing if not thorough in describing the situation and trying to persuade his master not to go through with it. Still, there was a difference between heading for certain death and the actual feeling once you got there.
The poison burned in his throat and feelings of madness began to sink in. It was like dementors had swarmed around him, his worst thoughts swimming in his head. Memories came flooding back to him as his body heaved and choked from the liquid. Regulus remembered the day Sirius left for Hogwarts. He remembered the night he helped Sirius escape, despite every piece of him wanting his brother to stay. Or at least to take him with him. He watched back the memory of his mother burning Sirius off of the tapestry and making it very clear that he was no longer to be considered Regulus’s brother. He could feel the searing pain of the dark mark being burned into his skin as he relived those moments.
It wasn’t just the memories. The thoughts were just as bad. Voices telling him he was a coward, that he was taking the easy way out, that his plan wouldn’t work and Voldemort would succeed anyway. His brother’s voice telling him how disappointed he was and that this didn’t make up for what he had done. His cousin’s laughter, cackling at his pain, as he drank the final cup of the poison, now struggling to breathe.
He needed water. This was what Kreacher warned about the most. The elf had warned him that summoning water would not work but that he wouldn’t be able to survive without it. Unfortunately, he had also warned Regulus about the mob of inferi waiting in the lake. He knew it was futile but he tried to use Agumaneti anyway. It didn’t work. Still, he needed water. He felt as though his insides were on fire and water could be the only cure. He did the only thing he could think of and dipped the goblet into the water. He didn’t have a chance to drink the water before bodies began to pull him into the water.
Regulus had been prepared for this but he hadn’t expected the dead bodies to be nearly as strong as they were. It only took a matter of minutes for him to be dragged far enough into the water that his feet couldn’t touch the floor. He went to reach for his wand but an inferius gripped his hand and his one hope for salvation dropped into the bottom of the lake. His only hope now was to swim for it. The issue with this was that he was incredibly weak from the poison and still felt like he was about to drop dead. Which, considering the circumstances, was in no way a stretch. Regulus attempted to paddle away from the monsters but his attempts were futile. The inferi all grabbed at him from different directions and he struggled, attempting to keep his head above water. He attempted to kick the undead creatures and release their grip but there were too many, surrounding him like an army. A hand pushed his head under water, forcing him under. A memory resurfaced.
Regulus thought back to a time when he was a child and a summer day at the beach. He had been terrified of the waves but Sirius had insisted that he stay and play with him in the water. They splashed each other and got to pretend to be normal kids for a little. He had freaked out as a wave came crashing towards them. Sirius had tried to keep him safe by pushing him under the water instead of letting him flounder and risk getting carried away by the wave. Regulus had coughed and choked on the salt water and Sirius had gently led him out of the water and to the safe shore. Of course, it only took a moment for their mother to shout out and blame Sirius for playing too rough with his little brother. Still, he had always remembered Sirius flashing him a smile as he was scolded, telling him silently that it would be okay.
As the water filled up Regulus’s lungs, he just closed his eyes. If he used his imagination, he could pretend that it was just Sirius pushing him under the water to protect him. He would be safe on the shore soon.