As the other Sons of Fëanor, Caranthir was bound by an oath to recover his father's Silmarils, which had been stolen by the Dark Lord Morgoth. This oath took the seven brothers to Middle-earth during the First Age, where they established realms in exile, waged war against the armies of Morgoth, fought their own Elvish kind, and eventually brought ruin upon themselves.
In First Age c. 420, Caranthir rescued the Edain lady Haleth and her people, the Haladin, as they were besieged by Orcs. When he saw the valour of Men, he offered the Haladin free lands in the North. However Haleth, thanking him, refused and left.
As a member of the House of Finwë, Caranthir's father-name was Morifinwë ("Dark Finwë", a reference to his dark hair). His mother-name was Carnistir ("Red-faced"). The name Caranthir is the Sindarin translation of his mother-name.
Finwë = Míriel | | Fëanor = Nerdanel | _________________|________________________________________________ | | | | | | | | | | | | | | Maedhros Maglor Celegorm CARANTHIR Curufin Amrod Amras | | Celebrimbor