A strange girl who lived in a forest outside of Blue City, Fenis seemed to be able to talk to R.D.'s Liger Zero. She led RD. and the Zoid to a place in the forest where an ancient Zoid was resting. While RD fought Blake, she tried to revive the ancient Zoid, seemingly praying to it, apparently with some help from Matt who somehow heard her voice.

The Zoid was the Jet Falcon which was able to fuse with the Liger Zero to form the Liger Zero Falcon.

While not explicitly stated, it was implied that Fenis was somehow connected to the Fire Phoenix. Evidence of this that she was convincing RD not to run because it's not what his partner would've wanted. Also, when RD (in his mind) told the Fire Phoenix of his success with his new Fuzor, it was Fenis (also in her mind) who replied. Later, in the final scene of the episode, RD discovers her hairpin, a phoenix feather, on the ground after she leaves and begins to think that she herself was the Fire Phoenix in human form but immediately discards the idea.

(Source: Wikipedia)