Step1: finish anime
Step2: Look for smutty fanffictions
Step3: Write some smutt yourself XD
Also, I CLAIM PAIRING! I haven't seen any Pace/Luca here so, I guess that makes me first. It's kinda odd that I used this pairing as I'd sooner ship Luca x Felicíta. But this is what my muses whispered to me, so enjoy the smut!

He should have seen it coming. They were all alone in the kitchen. He knew what he wanted when he locked the door behind them. He had seen it in his eyes. That unsatisfiable hunger of his would be the death of him. He didn't want him. He only loved Felicità. But than why could he never resist the man he had grown up with?

A moan escaped his lips as Pace's lips caressed his neck. "You like that, Luca-chan?" The brunette asked. "I- I told you not to call me that." The raven man tried to say, but his words were heavy with his breathing. His face was a lovely shade of red. At least it was to Pace, who was standing behind him, one hand holding his wrist, the other under his shirt, tracing his abs. Pace's lips licked hungrily at his earlobes and the brunette nibbled a bit on them.
Another muffled moan escaped his lips. "P-Pace. Please stop." He begged the tall man.

Pace turned him around and kissed him on his lips. His tongue flicked over Luca's bottom lip, asking for entrance. Luca didn't want to, but he could only open his mouth. He couldn't resist his childhood friend. Not when those hungry eyes were staring into his soul. Whenever he saw those eyes, he was overcome with an unknown force. The need to make the other happy, no matter what it took. He closed his violet eyes as Pace's tongue slid inside his mouth and explored every nook and cranny. To his surprise, he found his own tongue entering Pace's mouth and exploring it as well. Suddenly Pace pulled away. The sudden loss of contact made Luca whimper a bit, his tongue still lingering on his lips. "Your words may say stop." Pace looked at the shorter man with a mischievous grin. The kind someone has when he is in full control. "But your body says differently." He said, rubbing his knee between Luca's legs, earning him another moan from the raven. That's right, he was hungry too. Whenever they got to this point, Pace's hunger found his way into him and he too was taken over by it.

He looked at Pace, his purple orbs filled with lust and desire. The brunette looked down at him and took his hat off. He ran his big hand through the black locks and smelled them, placing a kiss on the other's forehead. "I love the smell of your hair." He said, placing his hand on Luca's neck, pulling him closer. Their lips met and Luca wrapped his hand around the taller man's neck, deepening their kiss.
Pace's other hand slid under Luca's shirt again, sending a shiver down his spine. Pace broke their kiss again and while Luca was still wondering why, his shirt had already come off. He shivered when the cold air hit his skin, but Pace pulled him close to him, sharing his warmth. The kissing resumed and Luca was tugging at Pace's shirt now, wanting it off. The brunette obliged and Luca took a moment to stare at him. He was beautiful. His muscles showed perfectly, without making him look bloated. He followed the happy trail with his gaze. Pace just stood there and let those violet orbs violate him until Luca placed his hands on the brunette's hips and pulled him closer. 'Who was really the hungriest now?' Pace thought, a small smile on his lips as Luca's lips pressed themselves against his.
Their kisses became even more heated. Pace's hand traced Luca's side and the other caressed his back. It slowly crept down, to the hem of Luca's pants. Luca moaned into the kiss when Pace's hand slid in his pants and caressed his buttocks. His pants were already tight with need, their bodies pressing and rubbing against each other in unison. Suddenly Pace slid a finger inside, making the other gasp. "I-idiot! A-at least warn me before you do that." Luca protested, but he couldn't help moving into the motion of Pace's hand. "Sorry." Pace said with a apologetic grin and kissed him again.

One hand was in Luca's pants, the other held the raven's neck, and his knee was rubbing Luca's crotch, their lips never separating. The sensations made Luca shiver in ecstasy. His pants were feeling incredibly tight and Pace could feel the raven's hard-on rubbing against his through the fabric. He couldn't take much more of it.
In one fluid motion he yanked Luca's pants down and his boxers with it. Luca's member bopped up and down a bit from the sudden pulling motion. He blushed a ferocious bright red and shivered in the cold air. Pace lifted Luca up and put him on the counter. He slowly licked, nibbled and sucked his way down. First the shoulder, then the collarbone, his nipples, his stomach. His hands rested on Luca's hips. The raven felt the other's warm breath on his hard member, making it twitch eagerly. Pace smirked and stuck his finger in the Limone pie batter, and rubbed it over Luca's member, then the it. "Sweet," He said before taking it in his mouth entirely. Luca bit his hand, trying not to moan too hard, but to no avail. The gates of Heaven were being opened! That was the only way he could describe the sensation.

Pace's mouth felt so warm and good, his tongue never failed to tease and please him. Luca's moans grew louder and heavier, signaling that he was close. "P-Pace!" His hand grabbed the others brown locks, trying to get it even deeper inside. But then Pace let go of him and stood up. He looked at the gorgeous face Luca was making. Eyes half closed but filled with need and desire, a shade of red on his cheeks, mouth slightly open. He even drooled ever so slightly. Pace cupped Luca's face and rubbed the saliva away with his thumb. "Not yet my~sweet~Luca." He said in a sing-song voice.
He placed his lips against Luca's again and was immediately allowed entrance. Luca's hands moved to Pace's belt, trying to get it loose, while Pace's hands traced up and down Luca's legs. Luca finally got it open, mentally cussin' at the bloody belt, and Pace took his pants off. He wasn't even wearing underwear. 'Hungry bastard must have planned this.' Luca thought. Not that he minded. At least not anymore. Pace's member was fully hard as well, and quite the sight. Unlike Luca, who was still as smooth as the day he was born, Pace was trimmed. He was a little envious at the brunette for it, after all, he was the oldest.

Their lips reconnected and their members rubbed against each other. The brunette dipped two fingers into the batter again and brought them to the spot between Luca's legs. A gasp escaped his lips as Pace slid them both inside. When he felt the raven to be ready, Pace removed his fingers, earning him a small dissatisfied groan from the other. It was short-lived however, when Luca was turned around by the taller man and felt Pace's arousal pressing against hole. Pace kissed Luca's neck as he slid it inside.
Luca grunted at bit at first, his body still adjusting to Pace's massive member being inside of him. The brunette rested a moment, allowing the other to adjust while gently caressing him. He kissed his neck again. One hand trailed down and grabbed Luca's member as he began moving. It felt so good inside the raven. It was warm and tight. The sensation filled him up and still left him longing for more. But he held back. Just until Luca would be ready for more.

La Forca wouldn't have to wait long when Luca whimpered "Faster" and "Harder". Luca loved the feeling of the other inside him too. He could feel it slide back and forth and in and out. And then it happened. A loud gasp came from deep inside him when Pace hit that magical little spot inside him. Pace smirked and thrusted. He hit it again. He kept thrusting against that spot while pumping the other's member simultaneously. They were both on the edge, the air heavy with their breathing.
Pace pumped and thrusted even harder now. Both were moaning the other's name. Pace lifted Luca's legs up, fully supporting the other. It pushed them both over the edge. Luca's cum shot through the air and straight into the batter. Pace filled Luca's hole completely. Luca could feel the white goodness streaming inside him. Pace put him down again and kissed his neck and gently thrusting before finally pulling out. Both were panting heavily. "I- I love you." Luca finally managed to say. "I love you too Luca-chan." Pace responded and kissed him again.

~Later that day~

Pace was sitting at the table, a big Limone pie in front of him. "Ooooooh! De-li-cious!" He chanted. "Luca-chan's Special Limone pie. Daisuki!" Luca just stood next to him blushing lightly. "Oh? There's still Limone pie?!" Libertà said and walked in, Nova behind him. "Can we have a piece?" The blond asked. "It's mine! Pace shouted, lifting the plate out of Libertà's reach. "Eh? Don't be like that. Just a little piece." Libertà continued. "No! This is Luca's special Limone pie." "What's so special about it?" Nova asked. "It- uhm has a special ingredient." Pace said. He looked at Luca, who hid his crimson face in the shadow of his hat.
"What's going on in here?" Felicità was standing in the doorway. "Ah Princess. Pace won't share." The blond answered. "Pace, surely you could spare a little piece?" She asked the brunette. "After all, you've got an entire pie." "No! It's special!" "Special?" The red-head asked. "Apparently Luca baked it just for Pace." Nova answered. "It would seem like he added a special ingredient too." He continued.
Felicità's eyes lit up. "A special ingredient?!" In one jump she was in front of Luca. Cooking was one of her hobbies and she was always eager to learn more. "What did you put in it? You have to tell me!" She practically begged him. "M-Milady! I can't say. It- it's a secret." Her attendant responded. The red-head pouted. An idea formed in her head. There were other ways to gain information. At least for a contractor of the Gli Amanti.
Luca saw the sly grin on Felicità's face and realized what she intended to do. He tried to stop her, but it was already too late. A gush of blood like the Niagara Falls streamed from her nose as she fell to the ground unconscious. "Fel!" "Princess!" Nova and Libertà called, but she wasn't responding. Her leg was twitching slightly and the duo picked her up and rushed her to a doctor.

"M-Milady..." Luca just stood there in a stupor until he felt Pace's hand on his shoulder. "Don't worry." The brunette said. "Don't worry?! Milady just read my heart! And judging by her reaction she saw everything! So how can you be so calm?!" Luca shouted. "Because I have you." Pace answered, leaving the raven speechless. "Because I will always have you." He wrapped his arms around him and looked into Luca's watery, violet eyes. He placed a gentle kiss on his forehead. "I love you. My~sweet~Luca."

So? Did you like it? This is my first time actually writing smut. Though I have read more than my fair share of it. :3
So don't be shy and just leave something in that magical little box.
Now if you'll excuse me, I need a shower. :p