Both are villainous animal warlords from 2000s-2010s pieces of 3D media that resign in China and make usage of large forces of Gorillas

From a young age, they would have a fascination with fireworks, however, they would soon get their whole view around them shattered because of others (Shen learning that if he continued to work with fireworks, then he would eventually be defeated by a warrior of black and white while Panda King would attempt to sell his own fireworks to the nobles only for them to ignore his sell attempt due to his poor status), this would cause them to go into a fury and cause them to go out and attack villages (Shen attacking Pos village and Panda King attacking other villages)

They would both attack the protagonists parents with a United group of baddies (Shen and his wolves and Panda King with the Fiendish Five) which would result in the death of someone close to the protagonist (Shen and his wolves killing Pos mother and more pandas and the Fiendish Five killing Slys parents) before seemingly going off radar

Eventually, after quite some time, they would catch the eyes of the protagonists whose parents they had killed, now utilizing tools which they had spent a while working on and perfecting, which utilized the fireworks that they loved (The Firework Cannon and Flame Fu), where they would face off in their current base of operations, until they were eventually defeated.