Hello! We remember reading your speculations with a "You'll know soon ( ͡° ͜ʖ ͡°)". Some points were very close to the truth! :D
Super happy you love Serin so much! He deserves it. In our minds, we're always replaying possibilities to let him go on adventures as well! Even if not for long, perhaps there will be opportunities.
We're super happy you saw the brother's relationship as well! Even though all three of them are quite different in personalities, and thus may not seem too close at first, they share a family bond of absolute trust and care! That's something we wanted to portray ;D
For most of the time, you can survive on intelligence but... we suppose there is no reasoning when it comes to beasts that want to turn you into food.
Good luck on exploring the other endings! We suppose Serin's bad ending is a pile of misery but eh... the others are candy (we hope)!