The moment before a shockwave feels like any other. The air is still and the atmosphere quiet; but ponies complain even in quietude because the smallest things draw ire when there is nothing to compare them to. So when the first shockwave hit Bon Bon and Lyra's house, Bon Bon was in a snit. Lyra had forgotten, again, to do the dishes.
The shockwave rumbled through the house, shattering windows and rattling doors, making the rafters tremble and the joists rattle. Bon Bon felt it ripple across her, a hundred times thinner than a hair and a hundred times stronger than a sledgehammer. Then she was on the other side of the shockwave, pushed off her hooves so suddenly she didn't even realize it was happening, skidding on the floor over shards of broken windows and colliding with the wall.
Bon Bon was too dizzy to stand, but she hoisted herself upright using the windowsill and saw instantly where the shockwave originated. In place of Golden Oak Library was a fiery stump and billowing smoke. In the distance, there was an enormous black-bodied centaur, with red arms, a red face, and horns as tall as buildings. A purple alicorn smaller than the centaur's hoof fired a magical blast, and a beam of white-hot energy forced the centaur back. Bon Bon screamed, "Lyra! Get out! Run!" She stumbled toward the door, falling, lunging, careening, tripping, crawling, hurtling, escaping out the door and out of the house as the magical blast became an explosion.
The second shockwave, a ring of magenta force, ripped over the landscape. It lifted Bon Bon off her hooves again, throwing her across the street, pounding the air out of her and leaving her tasting blood from the fresh bruises inside her chest. As the shockwave slammed into the house, one of the corner posts snapped. The wall next to the snapped post buckled, and the corner of the second floor fell. As it struck the ground, the house groaned. The beams sagged, then splintered, then split. The walls crumpled, the thatched roof collapsed, and the house imploded, sending up a cloud of plaster dust.
Bon Bon lay in the street, face against the cobblestones, panting and aching, too stunned to cry. The house was rubble, and Lyra, her best friend, was underneath.
A third shockwave hit, another ring of magenta magic that picked up Bon Bon and flung her against the wall of an adjacent building. Rocks and splinters raked her back, and she tried to shriek against the crush of the wave. As she landed, she saw a fourth shockwave on the horizon. She ducked around a corner and dove into a small garden just as it reached her. The impact pushed her into the ground and shoved dirt into her nostrils.
Bon Bon cowered, heart racing, throat gasping, head covered by her forelegs, trembling from fear and shame. She was reminded of the last shockwave in her life. She had been Special Agent Sweetie Drops until the bugbear's escape from Tartarus. Celestia's immediate reaction had been to keep her agents safe by disbanding the agency, and Bon Bon hadn't challenged her. She could have talked Celestia into letting her attempt to recapture the bugbear. Even if Celestia had refused, she could have tried on her own. But Bon Bon had felt out of balance, frightened, and vulnerable. She had run. Running had kept her safe. Running had ensured that she had no friends who could be hurt. But it had also ensured that she had no job and no home. It had left her in isolation and despair and without even her own name. The bugbear's escape had demolished her life as quickly and thoroughly as the shockwave had demolished her home with Lyra.
Only when Bon Bon had resettled in Ponyville had she begun to recover, and no pony had been more important to her recovery than Lyra. But now, battered and bruised inside and out, Bon Bon felt frightened and vulnerable again. Running would keep her safe. She could run away from this life just as she had run away from her last. In her mind, she already felt her hooves against the road again.
But if she ran, she would leave Lyra behind, and Lyra was her best friend. Lyra had been her friend when she had been scared to have friends. Lyra mattered to her. And while she was hiding in the dirt, Lyra was still out there, still under the rubble, still trapped or hurt or even dead.
"Lyra! I'm coming!" Bon Bon galloped toward the heap that had once been their house and began heaving aside chunks of wood.
The next shockwave was the biggest. It was a burning fusion of magical forces, a thunderous clash that shook her skull and split her ears, a pressure that clenched her limbs and squeezed the air from her lungs, and it flung her back against the building where she had taken cover.
She got up, half-blind from the flash, coughing from the dust, body swaying, vision spinning, and kept digging.
"Lyra! Lyra! Where are you?"
Wall studs. Window curtains. Half a wardrobe. A lamp. The kitchen sink, filled with fragments of dirty dishes that no longer mattered.
"Lyra! Can you hear me? Lyra!"
There was a faint noise. Bon Bon stopped throwing bits of the house aside.
"Lyra? Was that you?"
She heard it again, a muffled call from underneath the ruined house. She cupped her hoof behind her ear. When she heard it again, she knew the voice, and she knew where to dig.
Lyra was under a doorframe, trapped by a broken rafter but mostly unhurt. Bon Bon threw aside the rafter and Lyra wriggled out.
"I was scared and hurt," said Lyra, "but I knew you wouldn't leave me."
"I was scared and hurt, too," admitted Bon Bon. "But you're my best friend."
A rainbow wave of harmonious magic spread across Equestria, and under its caress, they embraced.