So presumably at least those two were captures and tadpoled before (I think Astarion specifically was captured in BG, no?). With how quickly things events happen from Yartar to the attack and subsequent escape, I would be willing to assume that ALL playable characters were imprisoned and tadpoled before the attack, however, Karlach supposively jumped into the ship and got tadpoled sometime between the end of the intro cinematics and end of the tutorial, which just seems rather bit off considering what mindflayers seem busy fighting hellspawn and Gith intruders.
Honestly I find the Karlach thing to be the weirdest and most annoying timeframe aspect. It really doesn't make a lot of sense and I don't expect them to do much work to change that.
I agree. Such a weird way to introduce/communicate that it's Yartar. A little disappointing as well.
I hope that Yartar will have some importance later then. Even then, I'm unsure how they are going to tied it with the rest of the story with so little (or none from my knowledge) information about which city is being attacked during the cinematic. The average player won't see this interview and will think that's its Baldur's Gate. And, in my opinion, that's bad storytelling. But, I will hold my full judgement until full release.
Honestly I don't think Yartar will be important and I don't necessrily think it should be either. It's a city that was attacked and I don't think we as the audience really need to know much more than that. Maybe there'll be a brief explanation about the mindflayers getting more aggressive, or the nautiloid we were on breaking protocol with such a brazen attack or something, but in terms of the broader narrative, I don't think it's going to make much of a difference.
