Harold avenged the death of his sire immediately by capturing the two henchmen before they were able to escape Mr. Black’s mansion. From the henchmen, Harold learned the location of the last two elder vampires. Harold then ate the two henchmen and gained their strength. With the knowledge of the locations of the final two elders, Harold alerted the members of the church in the villages where those vampires resided.
The clergy struck with a vengeance when they learned the whereabouts of these two vampires from Harold. However, not only did the clergy find the two elders in their respective mausoleums, they also found most of their lineages and wiped them out, making the job of mopping up the rest of the vampires rather easy for Harold. He only needed to wait for one to make a little noise, and Harold would be there, and eat them.
Harold received a great amount of strengths and powers from his consumption of the remaining vampires. Some of his greater abilities include the power to fly, change form, turn invisible, make mortals do whatever he wanted them to, and locate other vampires and creatures of a supernatural nature.
There were many other very strange creatures that he realized existed. Most of then tried to stay hidden from the human populace, although there would be the occasional werewolf sighting or the blood golem trying to consume a human in order to have their skin so they could walk around and pretend to be a human. Then there were the mummies, although they were typically happy to be left alone in their desert with all their gold and treasures. They would occasionally kill or curse archeologists for theft of their rightful treasures. Sometimes they would even hunt down the thieves and take their lives and treasures back to their dusty tomb to be trapped for all eternity. Harold, luckily, was either on the good side of all of these other supernatural creatures and was unknown to the rest.
It was on December 12, at midnight, when Harold tracked down the last remaining vampire, and ate him. It was at this time that Harold became the last vampire to exist. Harold was effectively able to completely take over the human world, now that there were no more vampires to challenge him. It was also at this time that Harold gained the power to enter the dreams of sleeping humans at will, and have total control of his conscious while rummaging around in the dreams of the slumbering people.
He did not see much of a use at first for this skill at first. However, he decided to test it out on the first human dream that he was able to detect. So he went back to his coffin in his mausoleum and waited to detect a dream. Very soon he felt a rather strong dream coming from somewhere. He decided to join in and see what all he could do.