I can imagine Palter executing Mavis not to save the aliens, but simply to get rid of her because he can't stand her. Palter is far from a good person, especially for an invader, but thankfully the situation took a different turn. The time Palter was forced to spend with Mavis transformed his dislike into a small bond of friendship by the end of the game. In the end, Palter no longer hated Mavis, but felt a little affection for her. Even during the expansion, Palter was willing to sacrifice his own reputation for Mavis, Blanca, and Dilbert, not because Palter was a good person, but because the emotional bonds he created with these three became so strong that he wouldn't allow anything bad to happen to Mavis, Blanca, and Dilbert. However, Palter remains a cruel invader, at least that's how I see him.
Regarding Dilbert's origins, it's curious that he's always been a character who exudes simplicity and is easy to get along with, something that fits a rural setting.
Blanca is somewhat chaotic and even frightening; I'll never forget her dismembering poor Mavis, and now I know where those characteristics came from.
The effort in world-building is something I also greatly appreciate; I already liked the concept of the pink invading race, where the men are corpulent and the women have less of everything, haha.
An expansion in world-building always gives more life to a work.