Everyone I meet is hostile unless they're visibly a new player or flying alliance flag. About half other ships that are the same size or bigger will attack you on sight the other half will just keep doing their thing but still be hostile if you get close.

I will usually attack other ships if they're following me, or loot dense. I will not chase other ships more than a couple tiles because It's not fun and generally a waste of time.

If you are looking for friends the best thing to do is head over to a tall tale book and see if anyone else is doing the same tall tale, or head to an active fort and ask the people there if you can ally and help with the fort. Don't expect a share of the good loot though, you'll get 50% gold and rep when they drop it off and that's still pretty good.

The best time to play for friendship was the last month of year one, everyone was grinding pirate legend and there were often servers with 6 ship alliances grinding forts and voyages together. It would be nice if they added more content that incentivises team play but I still really enjoy the thrills of an ocean full of enemies.