Here's my guy, you can change his lore or mechanic if you want, but I think he'd be a pretty cool edition to the game and a connection between TR1AL & 3RR0R and ONAA: Origins. Lore: Scrap Bot was a C-Research Bot that was destroyed during Anti-Villain's raid on C-Research Facility 6. However, when Alton found the damaged robot, he decided to fix it up a little bit and give it a mind. PriOsm originally wanted the body so that he could actually interact with the physical world, but Alton gave the body to a clone of the Original Paraware. After the events of "ONAA: Origins" (and before the events of "Facility 6: a C.O.P.E. inspired game") Scrap Bot was dismantled for parts by the paraware clone as it transferred itself into the main facility grid via the electrical room. How it connects to PriOsm: Phantom Bot results from a glitch in PriOsm's systems that makes him hallucinate into seeing a nightmarish version of the body he once hoped to inhabit. Phantom Bot has a singular goal, put PriOsm into its "perfect" body. How does it do this? By eating him and completely overwriting his code so that Phantom Bot can take over PriOsm's being (because phantom Bot cannot interact with anything outside of PriOsm).
Mechanics: Phantom Bot will appear at random throughout the game, briefly flashing on the screen and immediately disappearing. Eventually, about halfway through the night, he fully activates and triggers a boss fight in which he basically does the flowery jarona thing a bunch, creating a quick time sequence where you must press keys at the correct times to deflect his attacks. Once you do this enough, he goes away, being completely eradicated from PriOsm's code. (also during his boss fight all other enemies are temporarily disabled).