Why was this written? Because Leonardo da Vinci's personal life in real life is stranger than fiction.
Gian Giacomo Caprotti da Oreno (aka Salai) is a real person, yet I took historic liberties concerning his personality as well as the placement of where he lived. Aka, I twisted a tiny bit of history to fit my fanfiction, but Ubisoft did that in order to make a game. I think I'll live.
Don't know who he is? Wikipedia is your best friend~

Enjoy~

Pairings:
Ezio/Leonardo
suggested Salai/Leonardo

Monteriggioni, 1490

"Ezio, please! Come, there's someone I want you to meet!"

I thought nothing of this strange little boy that walked up to me from the cozy shadows of Leonardo's workshop. Nothing but as to why he was there with Leonardo, of all people.

"Ezio, I'd like you to meet Gian Giacomo Caprotti da Oreno."

"Gian is fine." Piped the little kid, who smirked up at me cockily, as if already up to no good in his mind.

Leonardo leaned over my shoulder and whispered. "Salai (The Little Devil, loosely translated) works as well." Moving behind the one called Salai, he rested his hands on the boy's shoulders affectionately, his face glowing brilliantly.

"He'll be living with me from now on, learning what I've learned. Isn't it exciting! I've never had my own apprentice before."

"Isn't he a bit… young to be learning under you?"

"What do you mean by that?" barked Salai, glaring at me through his crown of thick curly hair.

I ignored him, just so he could continue to snarl at me. The kid's little spirit was addictive, at best.

"Well, why not? The sooner one starts to learn, the more they can retain, don't you think?" Leonardo smiled, giving me a knowing look.

I, too, started young in my learnings of the Assassins, so it wasn't that much of a far stretch to know that this 10 year old boy would be learning all the grand secrets and mysteries that Leonardo da Vinci would teach him.

"Don't worry, Ezio. I'll pay your Uncle extra for him staying in the Villa with me."

I smile softly, waving a hand. "Don't worry about it, my friend. You help the architect here do much better work than he would ever hope to do alone. You pay my family more with your brain and charity than your commission money."

"Your family's so poor now anyway, my Master's coin wouldn't hope to cover this moldy Villa's expenses."

"Salai! Behave yourself, please. Besides, it's not nearly as moldy as it once was… n-no offense, Ezio."

"Yes…" I was distracted by the smug look on Salai's face. A face of victory over something. Something that I had not figured out yet, but this kid had obviously snatched from me. But as of right now, I was too blinded by his age to know what it was.

Monteriggioni, 1499

Leonardo would be leaving the Villa today.
Ironically, today was the day I found the last codex page and me and my Uncle could finally realize what it was that my father had been searching for.
It doesn't stop the pain from swelling; I will miss that man.

I knock twice and reach for the door in order to retrieve the codex page I gave him to decode a while ago, but it's locked. "Leonardo?"

His door is never locked…

"Leonardo?!"

Sensing something wrong, I step back and glare at the door, feeling my talent drown my eyes to the point of stinging. The world went black, save for two blue figures about 3 meters in front of me, probably upon Leonardo's old bed. Two blue figures… laying on Leonardo's bed as one.

What is this fury I feel?

I stalk back upon the door and bang loudly three times, teeth gritting. One of the blue figures rising vertically from its laying position and walks over to the door, but it's not Leonardo… who is it? I rest my talent so that I may look at this man who dare lay with Leonardo.

"What is it? I would have thought you'd learn some manners from your little degenerate friends of yours."

I'm dumbfounded by what I see. Is this the same little child that stood before me only nine years ago? The same Salai who now has transcended all gender-bound beauty in this tender age of 19 where the line between fresh-faced boy and masculine man is blurred heavily. His sexy sharp chocolate gaze only falters me slightly.

"Where is Leonardo?"

"He's resting right now after decoding your precious little codex as well as packing. He doesn't have the… energy to indulge you right now." He smiled at me, grin like that of the sensual devil.

"Then give me the codex. We need it."

"But of course, Ezio. Auditore." He turned on his naked heel and stalked into the room, leaving the door open in some crude fashion of allowance inside. I follow loosely behind him, looking around for any sign of resistance or fight, but all is nicely tucked away in boxes or cases ready to be shipped. All that remains are inks Leonardo used in order to decode, the codex on a nearby desk that was always there, and Leonardo resting underneath a large blanket, smiling contently in his dreams.

Looking down at his near inhumanly relaxed demeanor, I unconsciously reached to touch one of his unruly locks of hair, but something stopped me. As if a barrier prevented me from stroking the hair of a man I've always held close to my conscious. What was this feeling of premeditated territory...

"Heeere? Don't you want this old codex? Take it, and leave Master alone."

Surprisingly, I do as he says. I take the codex using the hand that would have touched Leonardo… and as I do so, I look straight into Salai's eyes. And then, I understood. I see the same victorious eyes I saw in him as a child. The same piercing possessive eyes that had burned into the back of my mind those nine years ago were now present to me again. He had won something, and now I know what it was.

Leonardo stopped being mine nine years ago. He was now Salai's.

Clenching the codex within my hand, I took one last look at Leonardo and left the room, closing it behind me. I use my talent to look past the walls and at the two men immediately afterwards, just to get one last sense of their auras.

Salai's was now red and Leonardo's was yellow.

That evening after the codex were decoded and the mystery of the Vault uncovered, I returned to Leonardo's room, only to find that everything was gone. Disturbed by how quickly they had moved, I rushed outside to perhaps catch them leaving, and stilled my breath to see Leonardo sitting upon a carriage with Salai's packing the last of their things.

The scene was reminiscent of years before of me and him.

Walking up to the carriage, Leonardo spotted me and smiled, sliding off and trotting over to me. "I'm glad you managed to see us off. I'm so glad to have a larger place to work instead of my old place. And with Monteriggioni restored to its former glory, I no longer have reason to stay here and burden your Uncle, though I must say that it was a pleasure working on such a magnificently structured place."

You are not a burden, I wanted to say, but other things were on my mind, like Leonardo's happiness.

"You will be sorely missed, but you're more creative when you're amongst your element. You're sure to do wonders in your new workshop, Leonardo." I smile, resting a hand on my fr— on my target's shoulder, squeezing strongly. I can see a thin blush flustering to his face as he smiles, and I can see that little look that always means 'hug'.

I open my arms and he takes the bait. We stood there for a while simply embraced. I'm sure he thought of it as a farewell-until-next-time, but I saw it as that of the start of reclaiming stolen territory. Thus, I lean over Leonardo's ear and whisper in my more husky voice.

"He may be young… but I'm seasoned."

I can feel Leonardo jerk in my grasp, that jerk melting into a shiver as I loosened my embrace on him. Without giving the man a chance to speak, I turned on a heel and walk back to the Villa to ready myself for the trip to Rome.

I could feel Salai's gaze burn into my back, his anger of touching what was his piercing through my armor.
The heat felt delicious.