He tries twice more to take over Southern Rivers (and the world afterwards) in the next two games, but is once more hampered by Ty.
Boss Cass got out on the wrong side of the egg shell. He didn`t tiptoe around the shells either, he devoted his whole life to ruling the Southern Rivers, an aspiration which, thanks to Ty, has remained unrealized. After numerous failed attempts (including kidnapping the entire population of Burramudgee to create an army of uber reptiles) and jail time, it is no wonder that he has a transient work force. Karlos, Fluffy and even Sly have worked for him at one point, in addition to the Frills, Blue Tongues and other assorted baddies who remain regulars.
In Ty 1, he attempts to locate the Five Talismans so he can open the gate to the Dreamtime and banish all mammals to it, thinking himself a reptile due to his dinosaur ancestry. Indeed, Ty is at first unable to do much to weaken the giant mech he is piloting towards the Talisman Shrine, but Sly's timely intervention with his Doomerang provides Ty with the tools he needs to end Cass' madness.
He is busted out of Currawong prison by Fluffy in Ty 2, and immediately gets to work on a new plan. With the scientific prowess of the mysterious Karlos, and some technology he "borrowed" from facilities around the region, he invented a device that would let him fuse the best qualities of both reptiles and mammals, allowing him to create a race of super mutants. Cass plans to conquer the world with an army of enhanced reptiles, and kidnaps Burramudgee's entire population to assist in this. A team of Sly, Shazza and Ty, however, once more foils his plans, though if they send him to jail, he obviously isn't there for long, as he's free and once more reigning over Cassopolis by the time of Ty 3.
Night of the Quinkan
In the third game, he is not a boss as usual, but the ruler of Cassopolis. At first Boss Cass says he welcomes the Quinkan invasion, likely seeing a chance for power, though he changes his mind shortly after seeing one of his statues toppled over, seeing his new allies likely will just use him. He promises to help Ty find the kidnapped Shazza, but only if some favors are done for him first. He states, based on Fluffy's remarks, that he enjoys having Ty as a "slave," but nonetheless shocks everyone (especially Sly, who had worked with him for so long) when he actually gives Ty her location.
When Ty arrives at the Quinkan dimension, Boss Cass is being possessed by the Quinking, the first sign he may not have been showing his true intentions. The Quinking, via Boss Cass, states that the Quinkan were invited to Boss Cass' dimension, thus revealing Cass had been manipulating everything in an attempt to gain power yet again.
Sure enough, once the Quinking is defeated, Cass is revealed to have tied up Sly, Shazza and Fluffy, and is ready to kill both the Quinking and Ty with one shot. However, Fluffy jumped in front of the blast, being vaporised by it instead. Sly and Shazza broke free while this happened, and the former was seen grabbing ahold of Cass and dragging him off, likely to jail.
Boss Cass is ruthless in his pursuit of domination over Southern Rivers and purging it of its mammalian population. He will do just about anything to obtain power and achieve his goals, best seen when he actually brings the Quinkan to Ty's world, planning to use them to weaken Ty and the locals enough for him to conquer everything in the aftermath.
Boss Cass is, in Ty's words, "mean, arrogant, selfish, conceited, and a bully." Boss Cass is also racist, constantly demeaning mammals whenever he has the chance.
Boss Cass is prone to fits of rage when his plans are hampered, regularly abusing his henchmen. When one of his Frills suggested possibly trying another way of dealing with Ty in Ty 1, he was swift to issue a beating to the minion.
It is possible Boss Cass has some concern for others, if barely. He did seem to have some semblance of a relationship with Sly (who he had taken in and raised after sending the boy's family to the Dreamtime) during their partnership, refraining from beating him, promising Sly he would not be banished like the other mammals, and seeming genuinely hurt when Sly turned on him. However, the first could be the fact Sly was a useful henchmen, the second that he was quite possibly lying, and the third was either an attempt at pity or just the shock that Sly's unwavering loyalty had broken so quickly. Despite the likelihood they had some sort of familial relationship over the years, these ties clearly have been terminated by this point, showing how fragile any compassion Cass may show is to begin with.
He showed a hint of sadness and disbelief in his face when Fluffy sacrificed herself to protect Ty. It is very possible losing his two prime henchmen to Ty's cause has had effects on his psyche.
Role in the series
Boss Cass will make an appearance as a member of The Guild of Thunder after realizing that it was pointless to take over the Southern Rivers, and decides to do something much easier. But he actually expected that Bush Rescue would still follow him in The Troupe of Lightning to still be against him. While the Guild is often disturbed by his racist feelings against mammals, they are at least happy they are provided with more army forces. He does get along very well with Arpeggio due to them both being bird geniuses, but even Arpeggio does feel abit uncomfertable about Cass' "racist views", but is polite enough not to call him out on it.