I finished Mass Effect 2. Replaying it has convinced me, more than ever, that the Reapers don't really matter to this series. They are just a MacGuffin that force the characters to do shit. This is the 4th time I've played the game (and the first in nearly a decade) and what struck me most playing it this time is that there's next to zero central plot. There are like 3 total main missions involving the collectors, and the rest of the stuff is tangential. However, the "rest of the stuff" is so strong that it doesn't really matter that the central plot is kind of an after thought. This game has some of the best characters and best side-missions that Bioware has ever done, and apart from maybe Overlord, the DLC is also top notch. Samara, Thane, Tali, and Legion are standouts, but almost any companion character in this game (save maybe Jacob, who's just fucking dull) would be the breakout, fan-favorite, character in any game that Bioware has released since Mass Effect 3. Heck, I only played Andromeda 2 years ago and I can't remember a single fucking companion, apart from Pheebee, who I didn't even like that much.
The fact that Bioware didn't care about the main plot is underscored in the big "REAPERS ARE MAKING HUMAN REAPERS!" reveal. For some reason I remembered them devoting more time to it, so I was surprised to discover it's given all of 3 total lines of exposition which boil down to basically: "The reapers are making human reapers because they've always assimilated organic life to create more reapers.....just because." As far as I recall, the central plot of Mass Effect 2 is never mentioned again in Mass Effect 3 (there's a lot of talk about the Reapers enslaving other species, but I don't recall much about them creating new reapers based on other species.....but maybe I've forgotten).
That said, I haven't yet seen anything in the game to contradict my personal fan theory that the reapers act like they do because they are really fucking stupid. Or, more accurately, just ancient outdated AI that doesn't understand how organic life works so they do weird things that makes sense to their programing, but no one else: "We don't understand organic life, so let's create organic life in our image to understand it." That logic kind of would make sense to a machine, but would seem crazy and silly to anyone else. I admit that this is my own personal retcon, though, and likely wasn't intended by Bioware.
However, I was interested to see WAAAAAAAAY more evidence in this game to support the whole "Shepard was indoctrinated all along" theory, especially in the Arrival DLC, which I greatly enjoyed playing because I only ever played it once and I didn't remember any of it at all.
About to start Mass Effect 3. I've always said that ME3 is my favorite game in the series, so we'll see if that holds true after a decade. I can't remember a whole bunch of shit about ME3, as I've played it the least (just twice), so I'm excited to play it.