According to Bentley's research, The Grizz started as a low-level thug who was known for leaving graffiti tags. His graffiti was unexpectedly recognized by the art community as a new brand of pop art, which presented The Grizz with fame and wealth in addition to the newfound respect for his tags. However, this fame waned when the art community stopped taking such favor with his art. Angered, The Grizz returned to a life of crime and became a notable art thief. Working with Le Paradox, he made off with many of the pieces in the beginning of the game.
Sly 4: Thieves in Time
Sly and company first come across The Grizz as he is ordering his guards to prepare his next painting, which appears to be of a bound cave-raccoon. This cave-raccoon is revealed to be Sly's ancestor, nicknamed "Bob", who is rescued by Sly before The Grizz can order his guards to take him out after stealing his cane. Not dissuaded by this, The Grizz continues his operations in manufacturing more "cave paintings". It is also shown that he is responsible for the mass stirring of pterodactyls in the level when he arranges for their eggs to be stolen and used to create the paints.
Eventually, Sly and his allies make their way into The Grizz's machinery used to transport the pterodactyl eggs, but are separated when Murray is caught on one of the lifts. The Grizz prepares to make his leave when Murray confronts him atop a frozen pool. The Grizz declares his true passion for ice skating before challenging Murray, switching between attacking the hippo with icy winds and tasking him to follow his ice skating patterns. Eventually, Murray triumphs and defeats The Grizz with one final punch.
In the epilogue, it is mentioned that The Grizz still works on his "artistic style" while in prison. He also is attempting a singing career, much to the displeasure of his fellow inmates.
Like other villains in the game, The Grizz is marked by a massive ego demanding credit and accolades for his "art", which is deemed by virtually everyone to be terrible. This is also demonstrated by his attire, most notably the crown he had stolen from the museum (which is later used by Sly and the gang to transport themselves to Medieval England). Nevertheless, he possesses brutal strength and odd cryomantic abilities, as seen with the icy wind attack he uses against Murray during his boss battle.
The Grizz's most notable trait is his tendency of speaking in a hip hop/wannabe rapper manner. This of course leads to his trash talk and attempts to cement himself as a hip individual.