Loki never feels himself blink anymore.
Even when the twitch takes over the entire upper half of his face, he's practically immune to the feel of his eyes crashing shut under his eyebrows pulling together. It's fast, and it's violent. But the sensation's drowned out by whatever causes it in the first place. That's a mystery to him. He's never figured it out.
It had started as an annoying, tweaking feeling in his right eyelid that came and went intermittently. If he was fast enough to catch it in the mirror, it looked like a barely noticeable, hardly visible thing that looked like an heartbeat under the skin.
It felt like someone pulling on his eyelashes. Loki fucking hated it.
That pulse was like an incessant buzzing noise, but in his eyes. It felt like it made his eyeballs vibrate.
When it didn't go away and then slowly progressed to a shuttered blink, he gave some thought to getting a little more sleep whenever he could manage it. But that didn't last long, just like any other theory of taking time to do anything but hunt.
Hunt, hunt, hunt. For the often benign-looking monsters that would terrify children with their brutality and infuriate him with their cowardice.
Loki never really registered the word "fury." He'd only really been able to think of it as this slow heat that built in his circulation until it was suddenly all a violent red froth in his system and his eyes were dead set on the goal. Even if he didn't know what the guy looked like yet. That sensation almost never surfaced in Loki as anything but a quick one-two: The sudden and almost painful looking grimace of what looked, for all intents and purposes, like a compulsive tic.
So that blinking gave way to twitching, which either made him look extremely nervous or just plain psychotic. He never really understood it so he couldn't shed any light on what brought it up in him (except that eyedrops didn't help, and neither did sleep, or less caffeine).
And he'd given up the fight against it eventually. It had become a part of him, a clear indicator of distress that ranged from stress to desperation, to anger or panic. That, or the adrenaline of catching up with a perp that he'd been chasing for days on end.
These days, on the rare occasion he sees the twitch for himself in a nearby window or mirror, he has a startling moment of clarity.
It never leaves his mouth, never turns into tears, and most certainly doesn't form into words. But he can't turn off that pent-up energy behind his stare, because how else would it leave his body? How else would he discharge those shards of thoughts and confusion? Those tides of words that he can't think of and would never form in a million years?
It's his only way out of himself. So he allows it.
He stops being aware of it, too.
It just…happens.