u/abgry_krakow87

A previous fan theory mentions that Doc knew the moment Marty's family spiralled out of control was the race w/ Needles and the accident w/ the Roll's Royce. Thus, he picked up Marty at the end of the events of the first film in the brief moment before Marty took Jennifer for a ride in the truck (where the accident presumably would occur). Later on in BTTF3 Doc accidentally shares about Marty's accident but he cant say anything more than that without effecting causality.

Also note that with George standing up to Biff in BTTF1 and Biff becoming more submissive, the Tanner family of bullies skips a generation (Marty's), allowing for lesser turds like Needles to fill in the gap. Needles obviously knowing how to get under Marty's skin to goad him into a confrontation, Marty needed to learn how to stand up for himself against from the bully opposite of what George did.

Of course Doc can't say that outright without effecting causality either, so rather he uses the incident with Marty Jr and Griff to do so. By having Marty take the place of Marty Jr, he's teaching Marty to stand up to a bully walk away "whatever happens, whatever asks for, just say no! You're not interested!" And to do whatever he can to avoid a direct confrontation, including the Hoverboard chase, because Marty isn't goaded into a fight (or a race or whatever else). So even though it ends with Griff and his crew crashed into the courthouse, Doc feels satisfied that Marty learned better to "just say no" knowing he would face the same choice with Needles. Marty needs to make the decision for himself to ensure the future develops as it should without Doc directly telling him what happens or what to do.

Obviously things went array with Jennifer getting picked up by the cops and Biff giving himself the Almanac, plus the trip to the Wild West. But all that also served to help reenforce Marty to learn how to better stand up walk away for himself so that by the time he was challenged by Needles, he wasn't "stupid enough to race that asshole".

On TNG we’ve seen a lot on Federation / Romulan politics and diplomacy. There is a good foundation of mutual respect, even though both sides don’t trust each other. But even still, we know the Dominion is willing to stick its hands into the affairs of others to cause drama and instability within the major powers.

In “The Search Part 1” Sisko presents the Defiant and with it, the use of a Romulan cloak “on loan” and under the operation of subcommander T’Rul.

The fact that Starfleet had secretly built a prototype of a planned fleet of warships “to fight the Borg” alone would be enough to cause a major incident with the Romulans. Yet, Sisko told them about it, convinced them to offer a cloaking device for it, put a Romulan officer on the bridge. With that officer also offering top secret info regarding the cloaking device that would compromise Romulan security/safety.

Of course T’Rul mentions that “Romulan interests are served too” in regard to info about The Dominion and also likely offering a hefty detail report about the Defiant and whatever else she learned about Starfleet. So definitely the “common enemy” trope is at play here and definitely what Sisko to convince the Romulans to play ball.

But of all the great things Sisko has accomplished, bringing the Federations biggest and longest enemy to the table to reveal state secrets and participate in a joint mission should be at the top.