WARNING: The following contains spoilers for Dragon Ball Super Chapter 78, by Akira Toriyama, Toyotarou, Caleb Cook and Brandon Bovia, available now in English through Viz Media.
Move over, Dragon Ball Z's Broly -- there's a new pettiest villain in town and his name is Gas. As the Heeters finally put their plan into action in Chapter 78 of the Dragon Ball Super manga, their loyal attack dog has received quite the treat. Now carrying the title of strongest in the universe, Gas finally gets to do what he always wanted by doing what he has always done: beat people up. When the Heeters say "punch," Gas says, "how hard?" and he has no desire for that to change, and his outrageous boost in power has Goku and Vegeta sweating.
Considering the Heeters' plan is to kill Frieza and take his place as the rulers of the galaxy, it makes sense they would prefer Gas to be the strongest in the universe, rather than Granolah. While other fighters might chafe at being a glorified henchman, Gas takes tremendous pride in his role as the Heeters' enforcer. Unlike Granolah, whose loyalty to the Heeters was shaky before he found out they killed his mom, Gas probably won't seek to use his new strength to do anything other than what he is told to do.
Despite Gas' overly serious demeanor, he allows his more eccentric siblings to hype up his dramatic entrance as the new strongest in the universe. His mere presence strikes fear in Goku and Vegeta, while Granolah hardly recognizes the fighter he's spent so much time with. However, it becomes clear pretty quickly that Gas has a score to settle with the Cerealian. Considering Granolah and the Heeters have the same goal of eliminating Frieza, it seems odd that they wouldn't work together, but Gas has been carrying a hate-torch for Granolah ever since they met.
While Gas does follow the orders to kill Granolah, he's also following his heart -- he despises the Cerealian for daring to work for the Heeters when Gas believes himself more than strong enough to work alone. Providing muscle for the Heeters is Gas' privilege and pleasure, and he never agreed with Elec that they needed Granolah's assistance. It's a shockingly petty motivation for the powerful villain, and the craziest part is that he's not kidding.
There's no evidence that Granolah has ever wronged Gas in any way, yet the savage beating the Heeter lays on him is definitely motivated by intense, prolonged hatred. When Goku intervenes, Gas doesn't waste time in trying to end the Saiyan's life, showing that his toying with Granolah is a special exception. It's a testament to how much Gas resents Granolah that he would be so unprofessional as an attack dog to go as far as playing with his food. However, this is basically Christmas come early for Gas, so he can be excused for indulging himself.
That Super's new villain has such a trivial motivation is… refreshing. The vast majority of Dragon Ball villains have grandiose plans of conquering and slaughtering, and then there's Gas who just doesn't like his coworker and has decided Granolah can’t quit because he's fired. If Gas manages to eliminate Granolah as he has dreamt of for ages, he'll likely settle back into his role as the enforcer -- Granolah appears to be the only subject in the entire universe on which Gas has an opinion.