Cal Kestis, a survivor of Order 66 had been called to Tatooine by the force. He couldn't explain why he had even been called there.

Once he arrived he discovered a one year old, force sensitive Luke Skywalker. Stormtroopers had killed his family, luckily Cal had made it just in time.

Cal took little Luke into his custody and set out to find a home for both of them. He successfully found one on the planet Bracca.

There he could work for money to support him and Luke both. That worked for a few months until Darth Vader finally got wind of his lost son's whereabouts.