They looked different. Which wasn’t unexpected, considering that they just crawled out of the darkest pits of hell - the place that even the gods didn’t dare to enter. Yet something was off, made it seem more unnerving than offhanded.
They laughed harder yet it sounded more jaded, harsher. They smiled more but it seemed more mocking, condescending. They went about their daily routines like nothing happened yet they seemed to excuse an aura around them that screamed danger - one that had always been there but now was so strong it made the others want to run and hide.
Their fighting style changed. Before sure they were powerful and amazing fighters but now? The monster would be dead in seconds. They were able to tell if there was a monster in a mile radius. They were able to hit just the right spots to make the monsters crumple to the ground with a hit. Monsters didn’t have hearts but somehow they managed to aim for it.
Before they worked together seamlessly like a well oiled machine but now their fighting styles changed with every slash from greek to roman and to something else that was just unique to them. Their plan changed with every stab and somehow they managed to keep up with one another - making it seem effortless all the while.
The first time they saw Percy kill a monster without lifting a hand and Annabeth taking her time to slash a monster to bits, they understood. Tartarus isn’t a place for humans after all. Percy and Annabeth were always fighters, adapters.
They made the greatest sacrifice of all. They sacrificed a part of their humanity.