Dark Daxter is Daxter's dark alter-ego, featured in The Lost Frontier. After falling through an open manhole and into the Aeropa sewers, Daxter was doused with a flood of dark eco, causing him to transform into an eight-foot mutant version of himself, now equipped with special abilities.
Additionally he underwent a personality change, during which he has an insatiable diet for dark eco and a grandiose self-image, believing himself to be the top of the food chain. Despite this, he still retains his intelligence, taking note of the fact that the laser lab was designed to contain dark eco experiments. Towards the end of each mission he will tire out and yawn before transforming back into his normal ottsel form (the former always taking place in an elevator).
While in his dark form, Daxter appears to appreciate his new ability, boasting about his supremacy. However, upon returning to normal form, he appears to be jubilant to be "orange, soft [...] cute, and cuddly", proceeding to curse the Precursors and complain about his worsened body odor, hangnails, and headache, the latter two from his giant claws and collisions with walls, respectively.
Dark Daxter was first played as during the mission "Escape from the sewers", taking place directly after his initial transformation, during which he had to navigate Aeropa's sewer system while fighting off voltaic eels and ghoul spiders, as well as turret defenses.
The second time Daxter transformed into Dark Daxter was at the abandoned research rig after the mission "Search for light eco", during the mission "Escape the laser lab". After wandering off from Jak and Keira Hagai, who had already resolved to leave the rig, Daxter instead took a gander at a control panel which he mistook for a candy machine. After failing to get the machine to produce candy, the machine activated, grabbed Daxter, stuffed a red ball in his mouth, and dumped him in a holding cell.
The holding cell was then inundated with dark eco, causing him to transform and bust out of the cell and into the laser lab segment. During this mission, Daxter again had to fight off eels and spiders, as well as tripodbots, while navigating around a giant decontamination laser, the batteries of which he manipulated to change the direction of the laser (also allowing him to break path blockages).
After being double doused, Daxter was now able to transform into his darker alter ego at will (or he had simply not chosen to prior). The third and last time that he transformed was at the old Aeropan barracks. After being grabbed by an Aeropan commando, he grew into twice the size of his assailant and proceeded to crush him, complaining that that particular commando was now "broken". Despite saying he was "still hungry" and wanted to go find more "meat snacks", Daxter was never seen actually eating any of his opponents.
Daxter proceeded on to "Smash the barracks", during which he encountered more commandos and gladiators, becoming separated from Jak and Keira once again, who had jumped through the teleport gate at the barracks and arrived at Aeropa. After the end of the mission, Daxter rode an elevator back to the gate, and back at Aeropa, was spat out from the gate, now in his normal form. He abruptly told Jak to close the gate, indicating his fear of his prey now that he was no longer in his predator form.
Dark Daxter has a set of dark eco-related abilities, as well as a couple basic controls. The first two involve dark eco bolts (), with which he can throw massive dark eco blasts from each hand, as well as frenzy mode (), during which he spins in a rapid manner as to take on the appearance of a large purple tornado. He is also invincible during frenzy mode, though unlike the dark eco bolts, this ability drains his dark eco meter (which can be refilled by picking up dark eco drops or by frenzying against dark eco crystals).
The latter two involve a ground pound ability (), with which he pounds both fists on the ground, which can both be used as an attack as well as to flip batteries on the floor, which can reverse the direction of spinning gates, the decontamination laser, or toggle laser barriers. The fourth and last ability is a pick-up control (), with which he can grab enemies and throw them back down (which is most useful with ghoul spiders, as they will leave behind sticky webbing capable of making web platforms in gaps in the ground, as well as slow down fast-moving pistons until they stay still).