3 years old:

Finally, Harry had fallen asleep and Sirius could hardly hide his need as he dragged Remus to their bedroom.

They shed their clothes and snogged furiously, treasuring their borrowed time. It must have been 3 months since Harry had started interrupting them. 3 months of no sex.

Remus started sucking him as he bit back a moan.

"Moony," he panted, "No...mmm...privacy...yes, there...charms."

Remus simply shrugged as though it didn't matter.

Sirius could feel himself releasing and moaned as loud as he could. F*ck the charms.

A knock at the door.

A sweet little voice.

"Uncle Moony. Uncle Paddy. I have bad dreams. I can't sleep."

Remus sighed and magicked his clothes back on before putting Harry back to sleep.

5 years old:

Harry was playing outside on his broom. Of course, he'd be fine. Remus rushed towards Sirius - they hadn't seen each other in 2 weeks and needed to be together. Now. This time, they remembered the charms and locked the door as well as casting a privacy charm. They stripped and after a quick rub, Remus let Moony out and entered Sirius.

Meanwhile, Harry had crashed his toy broomstick. He had grazed his knee and started crying. "Moony? Padfoot? Where are you?"

He ran inside and tried the door. Locked. The pain was really getting to him now so he let out his anger and the window smashed open by accidental magic. Remus and Sirius gasped and stopped as they could hear their Godson's crying. "Harry?" They dressed and rushed out of the room to attend to his wounds.

7 years old:

Sirius had Remus exactly where he wanted him: handcuffed to the bed. He explored Moony's body thoroughly before covering in lube and pushing into him. They rolled their hips together and had just got going when the doorbell rang.

"Moony? Padfoot? I'm back with Harry," called their next-door neighbours, the Grangers. They had discovered that they had a muggle-born and magical daughter and Harry and Hermione often went on play dates together.

They let out a frustrated cry and did their normal routine before rushing to the door.

"I can't wait for him to go to Hogwarts," groaned Sirius.

9 years old:

Harry was having a sleepover at Hermione's and they had a free night to themselves. Finally. They decided that since they had the whole night, they would take it slow.

Sirius ran his mouth along Remus' body, making sure to kiss each and every scar. He ran his fingers along each muscle before dipping his head lower and starting to suck him. Remus was just about to orgasm when Sirius couldn't stand it any longer and shoved Remus inside him.

"Want it rough, eh?" Remus laughed and moved in and out to a quick rhythm.

Harry seemed to have caught the flu and Hermione didn't want to risk being infected (not that Harry would have wanted to give it to her anyway) so, using his new key, he quietly let himself in and slipped to his godfathers' room. He opened the door and was shocked to see them sweating and moaning as something happened beneath the sheets.

"Moony. Pad foot." Harry called, "I have the flu and I need a potion. What're you doing?"

They both looks up to see Harry staring at them.

"Um...Wrestling?" Sirius suggested, "I'll be in your room in a few minutes."

11 years old:

Harry was finally at Hogwarts. This time, they were sure that they were not going to be disturbed.

Sirius slowly entered and they savoured the friction that they caused, bucking their hips and rolling around.

His hand wrapped around Remus and massaged him. He worked in and out and they finally had their first proper orgasm in years.

Bonuses:

13 years old, summer before 3rd year:

Sirius whistled as he stripped the beds with his magic. They were bundled up and almost in the washing machine (sometimes he really did love muggles!) when he noticed something on Harry's sheets. On closer inspection, it seemed he had his first wet dream.

After telling Remus, they decided to approach Harry together.

They entered his room to find him reading his latest book on magic life hacks.

"Harry?" Remus asked quietly, already feeling his cheeks heat up.

Harry smiled at them and motioned them to sit on his bed.

"Moony and Paddy," he said, smiling, using Sirius' nickname, "What are you here for?"

Sirius decided to bluntly get to the point, "Do you know what sex is, Harry?"

"Erm...Only that it is another word for gender."

A beginner, Sirius sighed. He decided to use the technical terms rather than the swears he normally used with Remus. After all, knowing the five swear words he had accidentally used in front of Harry was better than seven. Mind you, he was probably exposed to worse at school.

"Have you noticed your penis becoming erect?" Why didn't they do this as a class at Hogwarts?

Harry blushed and nodded.

Sirius continued, "Well, it's for a reason. Sex is when you want to have a baby," he decided not to go into the other use just yet, "If a boy and a girl, or boy and boy, girl and girl, if they take a potion, want to have a baby then they put their penis in a girl's vagina, release sperm and the egg is fertilised."

Harry blushed even worse but nodded again.

"But you can also do it because it feels good. Masturbation is when you pleasure yourself and is practically the only way to make your erection go down. You just...*cough*...rub yourself. Do you know if you prefer c**k or c**t?"

Remus slapped his leg and Sirius groaned. He had been so close to not swearing the whole time.

"What that?" Harry asked, bewildered.

Sirius was mostly happy because that meant that Hogwarts wasn't too bad for swearing.

"Forget it. Do you prefer penis or vagina?"

"I don't know but I will tell you when I know," Harry responded.

Just as they were about to exit, Remus added, "Oh and Harry, sex shouldn't be casual, it should be saved for someone you really love."

13 years old, during 3rd year:

Harry had made a startling discovery and had to tell Moony immediately. He was their DADA teacher and would tell Sirius after. He rushed to the classroom and opened the door to find Moony and Padfoot naked and Moony seemed to have his penis inside Padfoot.

"What are you doing? Is this sex?" Harry asked, shocked.

They hurriedly shoved outer robes on and turned to Harry, embarrassed and bright red.

"Um, yes," Sirius groaned, "What are you doing here?"

"I found out I'm like you. I'm gay."

They immediately brightened up.

"So who is it, who do you have a crush on?"

"Um...I don't really want to tell you. You'll take it badly."

Remus kindly said, "Harry, we will always support you, no matter who it is."

"Malfoy."

A/N: LOL. Imagine Sirius' reaction!

Also please vote on the poll on my profile for your favourite pairings. They will be included in my new fanfic