Date of Birth: 1480.
As evidenced by Leonardo's notes, the two hit it off almost immediately: "The second day I had two shirts cut out for him, a pair of hose and a jerkin, and when I put aside some money to pay for these things he stole the money out of the purse; and I could never make him confess although I was quite certain of it. The day after I went to sup with Giacomo Andrea, and the said Gian Giacomo supped for two and did mischief for four, for he broke three cruets and spilled the wine."
Leonardo may have described his apprentice as a "thief, liar, obstinate, glutton", and bestowed him with the nickname Salai (a little devil from the Romantic epic "Morgante") but at the same time the two were devoted to each other until the Master's death. Leonardo helped Salai with his painting compositions, frequently bailed him out of prison and left half his vineyard to Salai when he died. The apprentice even got to keep the Mona Lisa.
Either this was true love, or Salai had one hell of a sugar daddy.