AN: *MASSIVE SPOILERS AHEAD*
Okay, so we all know Bertholdt is the most dedicated to his mission, right? Well, despite that, he's still this awkward boy that's one step away from a complete nervous breakdown. So, in my mind, I imagine him taking walks in woods when things get too much and physically reminding himself who he is and what he's supposed to do.
Attack on Titan (c) Haijime Isayama
He curled in his mutilated fingers, forming a bloody fist.
He watched in wonder as the steam flowed gently from his wounds, leaving a comfortingly numb feeling behind. It was strangely therapeutic, watching the substance curl off his fingers and twisting in the air. The blood started to evaporate and his skin began to stitch itself together. Bertholdt glanced at the bloody mark left behind on the tree and couldn't suppress the choking sob that came out.
He collapsed onto the forest floor and rested his back against the tree he savagely attacked a mere minute before. He pressed his healing fist against his chest and willed tears to not flow.
The pain was a necessary reminder.
The steam was a necessary reminder.
"I'm not human." He whispered to himself. "I am a Titan. I'm not human. I am a Titan." He repeated the mantra over and over again until his wound was fully healed.
He watched forlornly as the last of the steam curled off of his fingers and dissipated in the air.
He didn't move away from his spot against the tree. He stretched his arm out, observing the hand that was once scraped and bloody.
The skin held no blemish, no flaw, no evidence that gave away it's previous state. Bertholdt sighed in vague relief.
It was a necessary reminder.
He was not human.
He cannot become too attached to the humans. He must not feel sympathy. He must not find comfort and happiness with them.
He must not end up like Reiner.
The thought of his friend caused the trapped tears to flow.
He must not end up like Reiner, who cared so much he was driven insane.
He must not end up like Annie, who became so cold and distant that she was hardly recognizable.
He must keep himself from breaking. He was the last thing holding their fragile group together.
He can't get too attached. He can't break. He can't leave Reiner. He can't leave Annie. They were all he had left.
He was all they had left.
Bertholdt held his fist to his lips and continued chanting a new mantra in between his increasing sobs.
A new promise to himself. One that he knew deep within his pounding heart he was unable to keep.
"I will not get too attached. I will not get too attached. I will not get too attached..."