For The Greater Good
It wasn't long after his mother died that Albus met Gellert, with his bright eyes, thick golden locks and cheeky grin he wasn't the sort of person you'd just look over.
He came with ideas too, outlandish ideas, he came up with new and better things each day. One thing he was set on though, was power. The problem with that was, he didn't know the right way to express things, which is where Albus came in, "for the greater good" is what he told him. What Gellert wanted to do, what he dreamed to do, had to be "for the greater good". Countless times Albus stressed that.
Albus had never viewed magic and muggle as he did, but the more Gellert spoke about it, the more Albus agreed. He'd told Gellert it was all "for the greater good" and now, since the first time he'd said those words, Albus was really thinking about them.
Gellert had come round to Albus's house the first day he arrived. The both took an immediate liking to each other, both were clever, both were powerful, both were great thinkers.
It was on the third day, Albus was sat in Gellert's room with him, they were practising spells, when the blond boy leaned over and pressed a kiss to his lips on a whim. At first, Albus was surprised, but Gellert flashed him a dazzling grin and Albus simply rolled his eyes, eyes twinkling with amusement, and something a little more.
Two days later, Gellert did it again, this time, Albus responded.
Days turned into weeks, and with each passing moment, Albus grew fonder of Gellert. They spent every moment of daylight together, often nights too, and when they were apart, even by just one house, they'd have an owl going back and forth for hours on end.
For Albus, it was refreshing to get away from it all, Aberforth, Ariana, all of the problems surrounding his young sister, he loved his family, but sometimes he needed a break. When with Gellert, he had no responsibilities, he could be a teenager, they'd mess around, they'd plan, they'd laugh, and they'd be together.
And then, Ariana. His little sister was killed, and it was his fault. All over something so pitifully stupid. Whether it was his curse or Gellert's it didn't matter, it had happened, it was all Albus's fault. He'd murdered his own sister.
Gellert left in a rage. Albus was left in grief.
It was after the funeral Albus destroyed everything that had to do with the blond, the letters, the photos. That when he realised just what he'd done, he'd let love blind him, yes, love. He had been in love with Gellert. He'd let the boy influence him into the Dark Arts, got him into planning on ruling Muggles. Albus had told him what had happened to his sister, what those Muggles did to her, and he had used that.
From that day, when the little sister he'd killed was laid to rest by her mother, Albus vowed to never let anybody hold so much power over him, to let himself be manipulated.
The real test came many years later in the from of the famous duel, Dumbledore and Grindelwald. It wasn't just a dark wizard he beat that day, it was a love gone twisted, it was a peace of mind. He knew from then on, that he'd never again do what he had. That was for the greater good.