Tarantulas is quite possibly the most treacherous and twisted Predacon ever! Between his sinister cackle and his sneaking about, you just know he's always up to something! The question is: what does he want and why? We learned in "The Agenda" that Tarantulas works as a Predacon covert agent who is not necessarily loyal to Megatron's vision of the Predacon cause. One of his primary motivations is his hatred of the "Aliens" (Vok). The other insight about Tarantulas' motives is that he is, in fact, a decendant of Unicron! So, Tarantulas seeks to destroy all of the Transformers abord the Ark since the resulting time storm would not affect him, only the Maximals & Predacons who decended from Autobots and Decepticons!

Character Bio from package "Tech Spec"
There are few Predacons spinning webs of violence and deceit as skillfully as the eight legged ninja warrior Tarantulas. After the quantum surge, Tarantulas was delighted to discover himself as a meched out arachnid with motorcross vehicle like capabilities. Instead of constantly relying on stealth and surprise, Tarantulas now races into battle on his wicked new wheels, converting into a new animalized robot mode that makes him virtually unstoppable in battle!