The Dragon: To Capricorn in Book 1, to Mortola onwards.
Dragon Ascendant: Subverted, he doesn't actually lead Capricorn's fireraisers after his demise, due to the fact that most of them perished in Inkheart. He instead acts as The Heavy, in terms of having a more active role on the frontline (compared to Mortola and the Silver Prince.
Knight of Cerebus: With the exception of sequences when he's incapacitated, he raised the threat level considerably. Though he doesn't actually harm anyone in the first book, in the second he kills Cloud-Dancer mid-way through the book, before pulverising Plot Armour by knifing Farid. In the third book, he is brought back by Orpheus as a Night-Mare, and is more dangerous than ever until Dustfinger realises who he really is and uses it to put him down for good.
Start of Darkness: According to Fenoglio, he has one of these, which is actually surprisingly sympathetic.