It is said that fire cannot kill a dragon, but dragons have never encountered fire like this. However, if we're applying science to Game of Thrones , it is worth it to ask how Viserion could ...

Look, I wasn't surprised when, back in season seven, Viserion's superpowerful blue dragon fire managed to cut through the Wall in the North because, well, it was made of ice. Also, blue fire is ...

They are a breed of dragon, whereas Viserion is something else entirely — he is a dragon that has been raised from the dead. As a result, he now breathes blue flames.