Animal!
Tier 1 boon or discovery:
A CR 1-2 beast such as a(n) dire wolf accompanies the adventurers for the rest of this region.
Animals which accompany the adventurers typically do so for as long as they remain in this region. The animal assists in combat, uses its senses and other abilities to aid the adventurers, and if large enough will allow the adventurers to use it as a mount. When bloodied, a boon animal flees.
A boon animal does not generally possess intelligence greater than those of a regular animal of its type, but there is a 50% chance that an animal understands basic commands and engages in crude attempts at communication.
Flying animals such as birds are especially good at warning adventurers of impending danger, and additionally grant advantage on ability checks made to avoid being surprised.
The Narrator is encouraged to invent colorful or thematic ways for the animal to be introduced.