Treeflowers

Treeflower is the love of Norbert's life, whom he met at an outdoor concert.

Once a hippie beaver, she successfully works in versatile jobs, e.g. as an elevator-music composer and a firefighter.

Treeflower has a kind personality, but then again, it tends to change somewhat because the most prominent thing about her is that she changes her job, clothes, hairstyle, etc. all the time.

Norb tries calling Treeflower because he believes it is she that has been pranking them. She isn't home, but her answering service says "Treeflower is off on another exciting adventure where she'll change her career and personality one more time.", which pretty much summarizes exactly what happens throughout the series.

Relationships
She and Norb are obviously on good terms, but Dag tends to annoy her sometimes or come off as weird. However, he is also her friend. In "Muscular Beaver 3", she saves Dag from falling to his doom, but Norb takes it the wrong way. She explains that she was just helping Dag by playing along with his Muscular Beaver fantasy so that he wouldn't hurt himself in the woods.