He and his younger brother Radu were held by the Ottomans as youths as collateral, the agreement with is father (Vlad II) was that Wallachia was to remain neutral in the conflict between Hungary and the Ottoman Empire. His eldest brother and father were allowed to leave for Wallachia, where they were also allowed to rule. When his father and brother were killed, the two were released and were allowed to leave.

After his father and heir apparent died, the Hungarians installed his cousin (Vladislav II) instead of him as the Voivode. Vlad, being the eldest surviving son of the previous Voivode, got very mad at this, and went back to the Ottoman empire to get support and troops to reclaim his birthright. It's extremely unlikely for the Sultan to give a former foreign hostage a bunch of money and troops if they weren't on good terms, so it appears that he apparently made friends with a lot of powerful Turks while he and his brother were hostages. Then he waited until his cousin was on campaign elsewhere and just barely took the capital in October. Unfortunately for him, his cousin took a huge L in battle, lost half his army and had to flee back Wallachia to muster more troops. Vladislav was able to defeat Vlad's remaining troops and drive him from the city by December.

Once again, he settled in the Ottoman Empire. Willingly. If they were mad that this dude wasted a bunch of troops and money for a victory that lasted 3 months, they didn't show it because he was able to freely leave the Ottoman Empire AGAIN because he heard his uncle-in-law (his late father's brother-in-law) was just crowned in Moldavia and he wanted to try and get in on that. He stayed there for some years, and as cousin Vladislav II's relationship with the Hungarians deteriorated, Vlad slid in and pledged loyalty to the Hungarians if they aid him in taking the throne. After killing his cousin and becoming Voivode with his Hungarian troops, he purged basically everyone in Wallachia that didn't side with him hard enough, people he personally disliked, and people he thought had something to do with his father's death.

To not get immediately rolled over to the Ottomans for allying with Hungary, Vlad sent tribute to the Sultan. The Hungarians got mad at him for this but they fell into a civil war soon after. With the Ottomans appeased and the Hungarians fighting each other, Vlad then went and just pillaged the countryside of his smaller neighbours, captured Moldavia at one stage, and executed a bunch of Transylvanian Saxons for some reason. The Saxons were neither combatants nor Muslims. Anyway, he got too big for boots and stopped sending tribute to the Ottomans. The Ottomans sent an envoy to ask him what the fuck he was doing, he had the envoys executed and impaled, and invaded Bulgarian and Ottoman villages along the border. That's where the 23,884 figure comes from, he killed a bunch of villagers and militia along the border. He then told everyone it was about honor and defending Christendom from the Muslims. The same Muslims that sheltered him, forgave a betrayal and had their messengers impaled. This, coupled with the Ottoman counter attack failing, is where the image of Vlad the Impaler defending Transylvania from the Ottoman hordes comes from.

Even after driving off the Ottomans, so many of his own troops defected to his younger, less insane and bloodthirsty brother Radu that he started begging Hungary for help again, but the new king just captured him and imprisoned him rather than deal with his bullshit any longer.