I recall the brothers say they're from a farm outside of BG, and by extension, so would Mayrina. We're given some details, so we'll likely get to visit. Much of 'Baldur's Gate' is outside the city walls.
Now you've got me curious about Green Lantern, I'll look up his motivation.
Ethel also seems to be aware her plot doesn't work well if you don't play along. She curses, kills the now useless brothers and departs. But your typical murder-hobo is going to take that as a sign she's walking XP with cool loot. Probably the worst thing she could've done, pique the interest of such a dreaded monster.
Yeah, I didn't hear the term "Fridged" until years later, but I knew exactly what it was referring to.
You're average murder-hobo is only going to resent being robbed of that XP...bro.
As for the geography of it all, I'm struggling a little with the scale, also not a new point of contention, living outside BG might be anywhere.