|For the Responder Protectron in Fallout 76, see Mr. Fluffy.|
For the radroach in Fallout 3, see Fluffy.
Dr. Frank experimented with brain graft techniques, which he used on a rescued bear, combining its own with a bovine brain and glands. This experiment was a success, and Frank named the bear-bovine combination "Fluffy."
At first, Fluffy was docile and even allowed Frank to climb into its cage and pet it. However, Fluffy soon began to exhibit fits of rage, forcing Frank to reluctantly put a shock collar on the bear. Not long afterward, Fluffy escape after the shock collar was ripped off.
Fluffy subsequently became the prime suspect in the deaths of two hikers. Frank reportedly acquired a "sneak peek" at a forensics report, confirming his fears that Fluffy had become irreparably violent. Frank began to search for Fluffy, and his investigation led him to Site Alpha.
James Kord, a U.S. Army soldier posing as a hillbilly to ward off unauthorized personnel, accosted Frank and warned him to leave, though he was unfazed and continued his search. Frank eventually found Fluffy's den, where the bear had made its home after escaping, and planned to sedate Fluffy for capture.
Fluffy's corpse still lies in the den, filled with crossbow bolts, though the skeleton of Dr. Frank is also nearby, showing that both of them met their end as a result of this encounter. The son of Fluffy, however, still lives, now known as a yao guai.
After the completion of Unsolved: Tracking Terror, Fluffy's cadaver is labeled as a generic "stunted yao guai."