- “I'm not going anywhere without my brother.”
- — Octavia to Indra.
Because of the one child law on the Ark, Bellamy and Octavia are the only known siblings among the Sky People. They are half-siblings.
Ever since Bellamy sided with Pike in Season Three, their relationship has been strained. After Lincoln's death, Octavia disowned Bellamy, blaming him for Lincoln's death. However, events have made Octavia overcome her own personal demons and restores her relationship with Bellamy.
Bellamy and Octavia reunite after not having seen each other for a year, when Bell illegally forces his way onto the 100 pod sent to earth. As they lost their mother, who was executed for having two children, both are thrilled to finally be together and free of the caste system of The Arc. Bellamy is incredibly protective of his little sister, who is an adventurous soul.
- Bellamy and Octavia Blake are siblings on the CW television show, The 100.
- Bellamy named Octavia. He had learned about the Roman emperor, Augustus, and named his sister after the emperor's sister, Octavia.
- Aurora, their mother, told Bellamy that Octavia was his responsibility.