Cyrus
Cyrus was a Scout Sergeant of the Blood Ravens, who debuted in Dawn of War II. Much like Avitus is capable of displaying only the emotion of rage, Cyrus provides the squad with a mix of bitching, morbidity, and cynicism, which causes him to play rather badly with the naive Thaddeus, and also causes Tarkus to call him out, forever demonstrating that the tac marine sergeant is the bringer of all that is good. On the other hand, Cyrus's outlook does play well with Avitus's. In short, Cyrus is more or less the direct opposite of most of Steve Blum's other roles. He's also notable hair-etical, like the majority of your strike force. However, he does call Indrick Boreale incompetent, which means that he can't be all that bad.
Surprisingly, the amount of irritation he evokes in most players is directly proportional to the amount of Cheese and explosives-based rape that he brings to your force. Simply put, in both Vanilla DOW II and Chaos Rising, Cyrus is almost always a necessary addition to any force, capable of ravaging just about everything with copious use of demolition charges, remote-detonated bombs, cluster mines, and sniper fire. Almost all of this can be done without breaking infiltration, making him equally capable at reviving fellow squad leaders, killing hordes, and picking off high-value targets. He's also one of the most resource-efficient ways to level enemy bases, solo whole levels, and kill tough vehicles, since refills for his explosives are scattered everywhere on the map.
While Cyrus was a hefty slice of cheese in Vanilla, Chaos Rising turned him into a colossal fucking wheel of dairy. With a relatively simple upgrade, explosives become energy-based instead of limited items, meaning that patience is literally the one thing that's required to kill everything, everywhere, ever. As if that was not enough, the upgrade also makes explosives more potent. Most everyone on your force gets something similar, so at least Cyrus is slightly more balanced with his comrades. Plot-wise, he goes Angry Marine on the as of a sorcerer who's stealing his scouts, and gains corruption of not brought along to kick the pansy faggot's ass. If he does go traitor, he cites the incompetence of Indrick Boreale and others for fucking up the sector and the Blood Ravens in particular. This indeed proves that he doesn't know what he's talking about, as disparaging the two best characters of the entire Dawn of War series is BALD and FEWLISH.