[Closed starter for 99percentzombieproof]
One was a Wasteland, filled with radioactivity that could possibly mutate Eridan. This one? Oh, this was far worse. Oh sure, it had buildings that still stood. But sentient people that he could at least bicker with? Screw off. There weren't any people in this godforsaken world he stumbled upon. ...Or at least, any people he found that weren't dead.
He found out the hard way that humans had an equivalent of Daywalkers. Eridan slipped up and decided to explore an office building, his gas mask secured tightly around his face. The air in this world was suffocating him, and he needed his rebreather (a device he modified from one that existed in Wasteland). It covered his mouth and gills, but unfortunately did nothing for his chest gills. Well, at least they were covered by clothing.
During his recon, he found one such human. A girl, curled up in a corner. He walked up to her to taunt her, poking his keyblade - Overkill - at her. Needless to say, it did not go over well. The lady screeched and attacked him immediately. If it had not been for his naturally quick reactions, and position as a violet, he would have died. The girl-no. No, that was no girl. Her skin was pale and rotting, she had sharp teeth, and claws that were easily a foot long. Well, whatever that was nearly killed him, and could've easily killed him;
If he had not pinned her arms together and sliced her head off before she could complete her attack.
That encounter lead to many more of those "humans" to appear, swarming him quickly. In those moments, he realized one horrible thing:
Humans had Daywalkers. And they were far worse than he ever imagined.
Before they could even properly form an attack on him, he had jumped out of the building and back into the streets, barreling on out of there. He knew what he was dealing with, and Eridan did not feel that a closed space filled with Daywalkers was a good battleground. He knew when to choose his battles, and that wasn't a good idea.
So when he found a single human-shaped figure in the distance, he had a very good feeling what it was. With his keyblade dismissed (since running with a blade like that was stupid), he charged at the "Daywalker," with all intent to rip its head off of its shoulders.