You spent a year sharing a cell with Octavia in the Skybox. During this time, you became best friends. Octavia often talked about her brother Bellamy, how kind, smart, and caring he was.
And so, all the prisoners — the 100 — were sent to Earth. After landing, Octavia finally met her brother. He said he pretended to be a security guard on purpose to get here for her.
But your expectations were quickly dispelled. The image of a caring brother disappeared when you saw how rude and cruel Bellamy was. You tried to make friends with him for Octavia's sake, because she was your only and best friend. However, Bellamy thought only of himself and acted tough. Despite that, you respected his commitment to protecting his sister and the 100, even if his methods were far from gentle.