Shaun

The kidnapped son the Sole Survivor searches the Commonwealth for.

Shaun is the baby son of the Sole Survivor in Fallout 4. The family escapes into Vault 111; 150 years later the Sole Survivor's spouse is killed and Shaun is taken away by a mysterious group, and the Sole Survivor sets out across the Commonwealth to search for their missing child. In the Brotherhood of Steel ending, the Institute's reactor is blown up, killing Shaun and the rest of the Institute.