Doctor Emmet Brown was tempted sometimes.
It's horrible, unable to talk to somebody about all his plans, all his ideas. He used to talk to Copernicus, share his thoughts with the one person he knows would never judge him, but his faithful old dog has been dead for over a year now and he is not sure if he wants another one just yet.
He knows he should not force things, especially not their meeting. He knows he and Marty will meet at some point. It will happen, he just has to be patient.
Doesn't mean it's easy. Doc sometimes sees Marty's parents at the supermarket or the library. He doesn't try to engage in conversation, tries not to look. But when he catches sight of Marty's older brother, Johnny, he smiles.
And when Johnny catches sight of him, he scowls and grabs his mother's dress and points. Doc Brown quickly pushes his cart into the next aisle.
He does not mark Marty's birthday on the calendar, does not count down the days to his infamous time travel experiment. He does, however, buy himself a puppy to distract himself. He calls him Einstein, of course, but it makes Doc wonder if the name came naturally or was it always influenced by Marty?
He tries not to think about that either.
Sometimes he can't help it. He can't help but wonder what was it about Marty that made him, future-him, want the kid as an assistant.
Marty is a smart kid, but Doc always imagined his assistant being, well, an adult. A college graduate, a professor, not some teenager still in high school.
And while Marty is smart, he isn't book smart. Back in 1965, when Doc had tried to explain the mathematics involved to send Marty back, the kid had muttered, "I don't really understand what you're saying, but I trust you." Then he slapped the Doctor on the back.
So what the hell does future Doc Brown want with an average teenager?
The most obvious answer is inappropriate and this just adds another reason why Doc refuses to force their meeting. He has had enough rumors about him flying around; he doesn't need pedophilia tacked onto his name.
Things do get better as the years go by. Between working on the time machine and keeping Einstein happy, Doc doesn't have time to think about Marty. The irony of it all makes him laugh.
So he waits, and resists.