He has black dragon tattoos across his chest and upper arms and carried a distinct ax.
He and the Irregulars appeared before Quinn Abercromby and his people, being mistaken as marauders. Van Zan asked to be allowed into Quinn's castle compound to rest and restock ammo on their way to London to kill the male dragon. After a heated discussion with Quinn, Van Zan was able to convince him that they could put an end to the dragons and was allowed inside. He made quite a first impression riding in on a Chief Tank with Alexandra Jensen flying in on a helicopter.
When the female dragon that had burned their crops began an attack run on the castle, he and the Irregulars sprang into action. The operation did not go well. One of their men was killed on the ground, forcing Quinn to ride out there and finish his duties. Two more of Alex's "jumpers" were killed by the dragon. Quinn and Van Zan worked together to lure the dragon into range of a harpoon gun and subsequently kill her.
Later on, Van Zan orders his soldiers to enlist the castle's best men but were warned if the dragon finds them, he will kill them and find the castle. His team is attacked and Van Zan luckily gets shielded by the fire when going underneath the tank but everyone else on his team is killed. After discovering that Quinn and the kids are trapped underground after getting away from the male dragon, he and Jensen helped them free them out of the bunker.