Once he arrived on Earth, Kragger immediately noticed that there might have been something between Shayera Hol and John Stewart. He was also concerned that Shayera living amongst Earthlings for so long might have compromised her, which could constitute a problem for the Thanagarians' plans. Kragger addressed his concerns to Hro Talak, and suggested that Shayera should be psychologically assessed. In response to such concerns, Talak dismissed and admonished Kragger, who still kept eye on her. He attempted to test her allegiance by trying to get her to kill an unarmed John Stewart, but she graciously refused, confirming his suspicions. When the Justice League escaped, Kragger hinted that Shayera might have known where they were, and when she subsequently evaded the implication, Kragger used her avoidance to induce suspicion in Hro Talak. Afterwards, Kragger used the tracking device he planted on her to find the whereabouts of the League. He took Shayera into custody for high treason, espionage, and consorting with the enemy, after revealing to Hro Talak that she aided the heroes. Talak punched him in the face in frustration, yet Kragger remained proud of himself.
Kragger led an assault team to raid the Batcave, but his forces were quickly overwhelmed. J'onn scanned Kragger's mind to find out how to operate his ship. Like all Thanagarians, Kragger had strong mind barriers, but J'onn eventually managed to break through. However, such violent approach left Kragger mentally impaired.
After the Thanagarian forces retreated from Earth, Kragger had seemingly lost his wings, he was fully connected to a machine that sustained him, and served as battle armor. However, Kragger's brain damage was too deep, and he was permanently confused. He had a deficient comprehension of reality, and was easily talked into joining Paran Dul's squadron to take revenge against Shayera. He was easily convinced that it was her fault that Hro Talak had died, and Thanagar had lost the war, which is arguably true. After Shayera surrendered herself, Kragger engaged her in an aerial battle, but Shayera disabled his flight pack and he fell to his death.
In Kragger's mindscape, J'onn saw a shattered statue of Hawkgirl, and a statue of Kragger and Hro Talak standing next to each other, guarding a gate. This depiction could be interpreted as an expression of Kragger's inner desires, hinting towards both sexual feelings for Hro Talak, and a wish to rule by his side, now that the only menace threatening that fantasy ― Hawkgirl ― was crushed, so to speak. This would explain Kragger's disdain towards Hawkgirl, and his constant attempts to undermine her, all the while trying to prove himself to Hro Talak. This is emphasized further when he immediately trusts Vixen after she claims to wish to kill Hawkgirl because they love the same man, drawing a parallel between the two.
“ Kragger, his character is kinda of our homage to Martin Landau in North By Northwest. He plays Hro Talak's right-hand man who probably is a little bit more than that — at least in his own mind, which is pretty obvious when J'onn gets in here, we see the two big statues with the crushed statue of Hawkgirl laying at their feet. A little bit of symbolism there, which amazingly went over a lot of people's head. ”
— Bruce Timm