Full name: Tairneanach
Tairn is a black dragon, which in the world of Fourth Wing means he is among the biggest and most dangerous dragons alive. His full name is Tairneanach, and his size alone is enough to stop a fight before it starts.
He enters Violet's story as a rescuer. During her first encounter with the dragons, Tairn saves her — and then does something even rarer: he bonds with her. That bond makes Violet a rider in the truest sense and unlocks her signet.
Tairn is protective, proud, and impossible to ignore. He is not a pet and does not soften his edges for anyone, but his loyalty to Violet is absolute once it is given. That protectiveness is the core of his character — he stands between her and anyone who means her harm.
Because Tairn shares a bond with Sgaeyl, Xaden Riorson's dragon, his connection to Violet ripples outward. It is part of why Violet and Xaden can reach each other's thoughts and feelings, even when neither wants to.