The game begins and ends at the mother's grave.

The last stretch of gameplay is a return to the path to the doctor's hut.

It becomes a plot point when they mimic the gnomes' god. They are squicked out when they become red too. At the end of the sequence, they pass a river that is completely red with blood.

Blood Is Squicker in Water: During the part with the battlefield of giants, the brothers has to go through streams that are contaminated with the giants' blood.

Bittersweet Ending: The father is saved and the younger brother has grown as a person, but the older brother is dead and the father is heartbroken over it.

He helps his brother cross deep bodies of water and protectively shields him from the troll.

Big Brother Instinct: The older brother is shown to be quite caring towards his younger sibling.

Beware of Vicious Dog: The brothers must get past a big dog guarding a farmyard by alternately distracting it and climbing straw bales.

Benevolent Architecture: The environment is conveniently arranged so that the brothers can just get through (even if the whole thing collapses afterwards).

Turns out that the girl is actually a spider monster that uses the form of a human to lure victims to her lair.

Bait the Dog: The girl the brothers rescue from the seemingly dangerous cult people is more athletic in every sense than both brothers combined.

Backup from Otherworld: The implications of the final sequence where the younger brother conquers his fear of water are that he's only able to do it because of the strength from his late mother and brother, as you have to press the older brother's action button to succeed.

Annoying Younger Sibling: The younger brother to NPCs more than his brother.

The other trolls you see appear to be miners with complex machinery, though of those, the ones you interact with directly are Dumb Muscle. He helps you along and you end up rescuing his wife from the other not-so friendly trolls.

All Trolls Are Different: The first supernatural creature encountered in the game is a friendly troll.

Game brothers a tale of two sons