Carlos feels that he always should have known this would happen. So many signs, simple yet obvious signs pointed in this direction. It isn't like there is anything he could have done to prevent this, he's only human, and he never figured things would turn this way.
He should have known when the sandstorms occurred, it had been such an obvious thing. He remembers how confused and scared he and the other scientists had been when Cecil left through the vortex and something else came through. Kevin's voice had been so upbeat and he seemed so confused as to why the equipment was outdated and 'dry'. Carlos hadn't understood that back then; the technology in Night Vale was as up to date as you could possibly get. He knew this couldn't be a doppelganger, because it had a different name, a different voice, and came from a completely different place. It scared him knowing that Cecil was possibly in whatever universe that Kevin came from, because who knew what that universe was like.
When Cecil finally did return he had sounded so frightened. Carlos had wanted to go see him, go to his apartment and check on his friend, but he couldn't get himself to do so. He knew people in Night Vale died almost casually, daily, and he feared that if he got too close to Cecil then it'd hurt like Hell when one of them finally did meet their demise.
Now he wished he had gone to his apartment, but what would he have said?
He hadn't known back then what he knows now. If he could only go back to that day and tell himself to go, go tell Cecil he cares about him, and that bad things are going to happen, and if they leave town now then they'll be safe.
Would Cecil have even gone with him?
Most likely. He loved Night Vale, but he was willing to follow Carlos into the darkness or any place actually. He had damned the town he called home the day he thought Carlos was dead.
It shouldn't have taken a year to get close to the radio host.
The day Strex Corp. came it had put everyone on edge. He could feel his heart pounding in his chest when he heard the stress and panic in Cecil's voice at the end of the program. Carlos had quickly sent everybody home, telling them to keep safe, because this was a danger that was out of their realm.
By then things should have started to make sense to all of them.
By then he should have been able to notice it, to realize it. Realize what the Pyramid had been talking about so long ago, that it had been warning them. Should have known that the angels had known this day would come. Known that the Man in the Tan Jacket had tried in his own way to prevent these events, but when Strex came closer to taking over he had given up and instead wished to just leave the human realm, because it would be turned into a human form of Hell. He should have realized why the people from Desert Bluffs all looked like manic blood stained versions of everyone in Night Vale.
He should have known the day he met Cecil, shook his hand, and heard him introduce himself.
"Hi, I'm Cecil Free"