I love talking to all the NPCs in Trails games.
I think my favorite thing about the Trails series is how it develops its world and characters, really taking the time to flesh things out. So many games have nothing but empty "Welcome to Port City!" statements or everyone giving the same "There's something about that cave to the west..." line. Trails will do a few of those of course, but there's a lot of people just going about their own business with their own issues and obsessions.
Putting all that effort into the NPCs really makes it feel more like a world and not a series of towns and dungeons designed for me, the player, to wade through. So many of those odd little NPC character developments have nothing to do with anything in the main plot, but you can keep following them, as long as your own character's story doesn't make you leave the town. Sometimes they pay off, sometimes they don't, but it makes it feel like a place.
And I think that really helps, because Trails for me relies on that buy-in on the world. When I think back on SC, there's a lot of arguments I could make as to why it's a lazy sequel. It has very heavy reuse of characters and assets from the first game. You're literally in the same country again, with the same cast except for one new guy. You go through the same towns again, the only really new stuff is some new dungeons that mostly look the same except for a color change.
And none of that matters. The reason I loved SC was being able to go back to that world with those characters. And it's not just the major ones like Estelle, or Oliver. It's also the little things. It's the wannabe treasure hunter who I could keep checking up on in the museum having the treasure examined that came from a sidequest in the previous chapter. It's the aspiring reporter in Rolent who knows way too much. It's also sidequests like the one in Bose that was for tracking someone down based off a photo, and I knew who it was with one look at it. A lot of it are just the details, and NPCs are some of the details that makes these games special.