Author note:

Something that popped up in my head and refused to leave until I wrote it.
I'm relatively new to this pairing so consider this a form of testing the waters.
Enjoy!

You've got to be kidding me. This is, what, his third one today?
"Really Aloysius? You had to go for ice cream again?" Vincent D'Agosta asked jokingly as Special Agent Aloysius Pendergast folded himself in the deck chair next to him. "You'd better take that down a little, or you'll start getting fat!"
Pendergast looked at him, the ghost of a smile playing around his lips. "Technically speaking, my dear Vincent, this 'ice cream' is gelato. And why wouldn't I take advantage of it being free? After all, we already paid enough for our little trip. Besides," he continued as his smile broadened into a smirk, "with all our, ah, physical exercise at night I think it's unlikely I will be gaining weight any time soon." At this, Vincent laughed out loud, a blush creeping onto his face. "Did you just...? All right you got me there. But next time bring a cold beer for me as well, will you?" he grinned, before shaking his head and resuming to stare at the flock of seagulls, flying in the wake of the massive cruise ship they were on. They dipped and dived, making Vincent's head spin. After three days of doing absolutely nothing, it seemed his mind had lapsed into a lower gear too.
He averted his eyes and looked at Pendergast enjoying his gelato. It was over a hundred degrees outside, and some of it was already melting onto an exquisite golden ring around Pendergast's finger, dulling its shine. D'Agosta looked at the ring around his own finger. It was identical to Pendergast's one, safe for the initials engraved on the inside.
With a smile, Vincent thought back to the day on which he received the ring. That evening, after the guests were gone and the quiet had returned to the Dakota, Pendergast had announced he wished to take him to Africa for their honeymoon. D'Agosta had suggested a cruise on the Mediterranean Sea instead. Pendergast initially had some objections. But after the necessary bickering, had accepted on one condition…
"Father?" Both men turned their heads. Tristram had appeared behind the deck chairs, wearing flip-flops and swimming trunks. A beach towel was draped around his shoulders. "I just wanted to say I'm going swimming. So if any of you is looking for me, I'll be at the pool."

"Great, have a good time!" Vincent called after him. "But you should try not to- He stopped. The boy had already disappeared. "Well never mind then," he concluded his sentence instead.
"He should try not to do what, exactly?" Pendergast inquired. "Is this about the complaints we received? The –what did they call it- cannonball diving?" Vincent sighed. "Yes, but I guess there's no telling Tristram that anyway. Honestly, people these days are so fucked up they can't even let him have some fun?"
"I fully agree with that, Vincent. Besides," Pendergast added, "if they do not want their precious food to get wet, why are they eating at the very edge of the pool?" D'Agosta laughed and clapped his husband on the back, who winched ever so slightly. "All right, Aloysius so next time those idiots come whining about their food you tell them that. They'll love it, I'm sure."
"I'm looking forward to it," was Pendergast's dry reply.

Vincent was not sure when exactly the FBI agent had decided to bring his son along on their honeymoon. It was quite an unusual practice, even for Pendergast, and he wasn't sure he'd ever heard before of people bringing their kids along.
Not that he minded, though, for he loved the boy as if it were his own son. And, as became clear during their wedding feast, this feeling appeared to be mutual.

Tristram was the last one to speech. Nobody had actually expected him to, but after Proctor had finished speaking the boy had asked for the rooms' attention by softly tapping his spoon against his glass of sparkling juice.
Everybody fell quiet once again, and fixed their eyes expectantly on the boy. He blushed, clearly uncomfortable with being the center of attention. Yet, his voice -though soft- was clear and confident when he spoke. "My speech will not be as long as the one of Herr Proctor's before me -a laugh went through the crowd. Proctor, wasn't man of many words- so I apologize beforehand." The boy realized he was playing with the star sapphire on his left index finger, stopped himself and then turned to Vincent.
"Dear Vincent," he began. "I..." He broke off, his cheeks turning a deeper shade of pink. "I was supposed to say something about mister D'Agosta -Vincent- introducing me to pizza and me being very grateful for that. But you know, there is something much more important I would like to say..."
Tristram turned to address both D'Agosta and Pendergast. "Vincent, Father, I just want to say that I love you, both of you. And that I couldn't be happier today." Now, Tristram spoke fast, his words coming more easily. "Because as of today my father not only has a husband, but I also have a second father. I am so proud of you both... It will be an honor to be your son."
To his surprise, Vincent saw that next to him, Pendergast was blinking fast. The FBI agent quickly covered this up, however, by adjusting his tie. But Tristram had seen this, too. Before anyone else could react, he had made his way over to them and tightly hugged first Pendergast, then Vincent.

Pendergast could've decided to bring Tristram at that very moment. Or perhaps...? No, not their wedding night.
Oh, God their wedding night. Vincent could think of nothing more perfect. Even though his head was already fuzzy from the alcohol, D'Agosta remembered every detail. They had danced to a waltz D'Agosta did not know the name of. Pendergast had led him, for he didn't know the steps.
Somehow, Pendergast had managed to fill their whole room with candles, so that as they gingerly picket their way across the floor passing the flames, the shadows on the walls danced with them.
When Vincent got tired, long after the music had stopped playing, he had put his head on Pendergast's shoulder. Pendergast immediately halted. For a long moment they just stood there in silence. Breathing in each other's smell, enjoying each other's company and being perfectly, completely happy.
Then they had made love. Until the sun rose in a fiery blaze and wrapped their bodies in its golden light.

Just before they fell asleep, Vincent had mentioned Tristram.
"Aloysius?"
"What is it, my dear?" came Pendergast's sleepy reply. It was followed by a soft kiss on Vincent's shoulder.
"So... Tristram?"
"What about him?" Came the muffled reply. Pendergast's lips were still on Vincent's olive skin.
"Right. Tristram. What he said this afternoon... Will you thank him for me?"
"Why won't you do it yourself?"
"Because I don't know whether I can without making a fool of myself. I'll probably cry," Vincent admitted.
This earned him another kiss, this time on his mouth.
"Oh, my dear Vincent I love you," Pendergast simply said as they broke apart. "And yes, I will make sure to thank him for you."
Vincent smiled, as he always did whenever Pendergast declared his love for him.
It was a sleepy smile, followed by "I love you too."