It happened when Sasuke was only five years old, happy to come home and practically skipping to his elder brother's room to greet him.
"Um, we were just, um… wrestling?" Itachi attempted to lie.
"That doesn't look like wrestling to me…" Sasuke's intuition was stubborn and unmatchable, even for a five year old.
"Um, I'll get going now…" the young man that had been on the receiving end of Itachi's "wrestling match" grabbed his clothes hurriedly and ran out of the room.
"What was it you were doing?" Sasuke innocently peered at Itachi.
"Gosh, you're too young for this talk," Itachi mumbled to himself, "Well you see little brother… that was a ritual to give and receive, um…. love!"
"Why would you have to do such a thing to give love? Don't mother and father give us kisses and hugs to affirm their affections?"
'He knows far too many large words…' Itachi thought as he tried to form his next reply, "Yes, that's what family does to show their feelings, but when you love someone so much that you want to, say, marry them, that is when you show your love in that way."
"Oh… Will I ever be able to do such a thing?"
Itachi smiled and poked Sasuke's forehead softly, "Of course, little brother."
"Then… Will you teach me?"
Itachi's smile quickly disappeared, "I might tell you how it's done when you're… ready to… I will never teach you the ritual, though, it's one of those things you learn by experience."
Itachi's words were not useless, for in the future, when Sasuke hit his *ehem* early puberty, his brother finally told him of the ritual. Sasuke was surprised, at nine years old, to find out that it was no ritual. What his brother had described to him four years prior, was none other than SEX.