Merlin was a man of great power. Oh, yes, great wizards had come after him.. Grindelwald, Dumbledore, even Voldemort-- but, being a man of great power, he was also a man of great arrogance. And he was rather sure that when it came down to it, he was the more powerful wizard. And that was something that drove him. He wanted so very badly to know if Albus would some day be greater than he was. If he would some day be more powerful. It was an exciting prospect. He liked to push, liked to entice. When he'd lived among the muggles for so many years, he had gotten himself into (and subsequently out of) more fights than he could remember. Not all of them very good or exciting, but all of them well deserved.
Perhaps that was why he insisted on doing whatever he liked here at Hogwarts.
Yes, yes, he was technically faculty, he was supposed to behave and set an example.. but. Well. Where was the challenge and the fun in that? Where was the excitement if you didn't push your limits every now and then?
And that was precisely why he was strolling down the main hall with Apparae at his side. The large, white horse that nuzzled him every now and again, as Merlin flipped pages in the book he was reading. He had been on his way to the library, but the care taker had found him (again) and had shooed him away before he could make it there, so he'd turned and kept going. The old man who kept the students in line was far too afraid to stand up to Merlin, so he settled with watching him go in another direction.