Before meeting Joshua Graham, Two-Bears-High-Fiving will walk out of Angel Cave, pump his fist in the air and immediately walk back inside the cave. He does speak the common language of the tribals though and as usual will say "Goot" or "Jah-at-tag".
This character is an indirect reference to the inkblot test that takes place during character creation. A common opinion among players is that the final inkblot depicts "two bears high-fiving". There is a popular mod available that changes one of the available choices to this, and the character is a direct reference to this mod.