Disclaimer: i do not own the 100 nor it's characters.
Thank a lot to Miss Pixie M for beta reading.
Clarke knew she had to get away, the guilt was getting far too strong. Bellamy may think that by saying he forgives her he could take it all away from her but he was wrong. He didn't understand what the choices she had made had cost her.
He had been her co leader since the start but he never did make those really hard decisions, when he had protected his sister and let people die he hadn't seen what the results had been. It was her, Clarke, who had ended Atom's life not him. It was on her hands that rested the death of the grounders; the deaths of some of the Hundred; most of all Finn's death, even Dante's was by her own hands and finally the deaths of the people in Mount Weather were the consequence of her own idea even if they had pulled the lever together.
Bellamy was a great big brother, someone you could always count on. He was a great leader in time of peace or where his sister was concerned but he was never the one who had to take the final decision to kill in cold blood or self-defense or kill people who were innocent.
She was becoming a monster. War made people become monsters. When she was on the Arc she had studied everything about atomic weapons and she always wondered what kind of monsters could have pushed the button to kill so many people. But now, she understood that when you want to protect your people you are ready to do anything.
On the Arc life was harsh but there was no war. War really changed people, before Mount Weather she was headstrong, idealistic and she did not understand the reality that Lexa was trying to teach her about. Now she finally understood.
It had been two weeks since she had left the Hundred and her mother. But now it was time to go back to Mount Weather and bury the dead and maybe gain some form of redemption. She knew she would always be haunted by the innocents but she owed it to them to give them a proper death, it was the least she could do.
Once she reached Mount Weather she devoured the first food she could find, she had only eaten berries for two weeks. Then she got straight to work. While she was digging she realised she was crying, the grief was overwhelming. That's when she began to understand why Lexa had betrayed her. When you are a leader you have to put your people before everything else, she had now sold her soul for her people. She began to forgive Lexa but even then she knew that would not be what she would tell the Commander if she ever saw her again. Clarke knew that in her place she probably would have taken the deal to protect her own people but the difference was she would have come up with a plan to help the Grounders even when her people were free. She had trusted Lexa; she would have respected the trust between them by her honour.
She thought she had known Lexa but the Commander was a different person. It became apparent when she said she had made the decision with her head and not her heart. Clarke could understand that but knowing that also meant that the Alliance had meant little to the Grounders. She thought that by helping to heal the Reapers or the trades the Sky people could offer in technology would have been enough to make a strong alliance. Or that the trust between both leaders would at least ensure a strong alliance.
But now Clarke realised that war changes alliances.