He was there, always there. By his side. Because he promised.
And a gentleman always keeps his word.
His wedding day wasn't an exception.
Diedrich stood at the altar, tall and dignified in his tuxedo, and watched as the bride walked slowly towards them. He didn't know what to do with his hands.
He glanced Vincent sideways; he had his own hands joined in front of him and stared at Rachel with an almost sweet smile on his face. Diedrich copied the pose. He even tried to copy the smile, but it faltered after just seconds. He was sweated and slightly uncomfortable in his new shoes, and the thought of giving his best man speech later didn't help him to feel more at ease. Good Lord, how he hated this situation…
After what seemed an eternity, Rachel finally reached the few steps that separated the main aisle and the altar, and started her slow climb, with the last notes of Mendelssohn's wedding march reverberating throughout Westminster Abbey. The slowness was calculated, of course, since she was to reach Vincent's side the exact moment the organ stopped playing; the Abbey's wedding organizer had insisted it gave more pomp and circumstance.
Diedrich had been at the rehearsal, of course. He promised Vincent he would.
He looked at him while the happy couple took each other's hands and smiled happily, and he had to place his own hand on his chest. Something had surely upset his stomach that morning, a too heavy breakfast probably, and now he had some kind of annoying flatulence. It was the most plausible explanation for that ill-timed pain in his chest.
He heard a soft whish of skirts by his side, and a quiet whisper directed at him.
"Rachel makes a really beautiful bride, right?"
He nodded, slightly turning his head to look back at Angelina, Rachel's sister and her bridesmaid. Her voice was tinged with sadness, but Diedrich didn't comment on it. When they both turned again to watch the ceremony, he knew the two of them had their eyes set on the groom and not the bride.
Rachel's face was beaming under the veil, her gaze for once bright with happiness instead of her usual witty glint. But Diedrich glanced at that familiar mole under Vincent's eye, and couldn't help but reminisce of the first time ever he saw the young British lord.
He was new at Weston then, and determined to not let himself down, no matter how arrogant where his new peers. In fact, he thought he had succeed when he finally faced Phantomhive. The boy was in his class, and he had made a name for himself before Diedrich arrived to the school: Vincent Phantomhive was charming, incredibly clever and cunning, and it was dangerous not to be on his good side.
The moment the German boy saw Phantomhive for the first time, walking across the patio as if he owned it, even daring to thread on the lawn (and he still wasn't a prefect by then), Diedrich added to the data he had "elegant and handsome". Phantomhive moved with the grace and laziness of a feline, stretching his arms over his head with a dramatic sigh, his long neck leaned back, drinking the feeble warmth of the autumn sun. Then he suddenly noticed Diedrich's eyes on him, and turned to look at the new student in the eye. At seeing his bewildered face, Phantomhive simply smiled, slowly and lazily as he seemed to do everything, and winked at him. Diedrich's heart skipped a beat.
He became "Vincent" in the intimacy only right before finishing college, instead of "Phantomhive", although he still refrained of calling him by his given name when there was someone else around. It sounded… too close. He wasn't allowed to be that close. Not when he knew from the start Vincent was engaged, same as he was, so this moment, this precise moment, would eventually arrive. But he promised anyway.
"You will be my fag, Diedrich, from now on. Without a expiry date. I need someone loyal by my side, and you are perfect for that. Am I being clear? Then, raise your hand and promise! Give me your gentleman's word on that."
The exact words. And he agreed, because he had lost to Phantomhive.
After college there was Cambridge, with its dark nights filled with soft whispers and bright summer days laying on the lawn and watching the passing clouds. He had been so happy at Cambridge. It still hurt remembering those days, they seemed impossibly far.
Afterwards… the two of them parted ways, each one attending the military academy of their fathers' choice. And two years more serving their countries abroad.
The last thing he expected was a letter asking him to be the best man in his wedding, with the warning in the post scriptum: You promised.
He had trouble matching that tanned face, just back from the colonies, with the youthful features that haunted his nights. But that mole was unmistakable. And that cheeky grin. And the naughty, amused look with which he stared at Diedrich, analyzing his own physical changes unabashedly, without hiding his interest. He still had no shame. Just like Diedrich had no pride.
The ceremony was finished in the blink of an eye, or so it seemed to the best man, lost in his memories. Soon Vincent was raising the bride's veil and sharing a kiss with her, in front of the eyes of the whole British high society. Diedrich tried his best at not to flinch.
Then, Rachel reached for Angelina's hand, glowing with happiness, and Vincent turned to look at Diedrich with a wide grin. He linked his arm with his loyal friend's, and winked at him, his grin turning into his usual naughty smirk at once. Diedrich closed his eyes and felt himself turn into a shadow while the guests started to approach them to congratulate the happy couple.