Summary: Gaius was old and afraid, but he wasn't stupid. There had been a time, in his youth, when he'd fought valiantly for what was good and right and the things he believed in. Somewhere along Uther's break with reality, he'd lost himself. It was time to find that man again.
Gaius was still waking up in the deep hours of the night, the only thing keeping him from crying out being years of control over himself. It was bad enough tonight, the memories of being beaten and almost drowned in a tub of filthy, stagnant water, that he gave up on sleep altogether. The hard cot he slept on did his injuries no favours, and reminded him too much of the floor of his cell for him to really get comfortable enough to fall asleep. So, he got up to begin preparing one of his tonics - Morgana's sleeping potion, a hangover remedy, anything to not be trying to go back to sleep. As he made to pick up an empty bottle to transfer the completed tonic, one of his still-healing injuries made itself known and he dropped the bottle with a hiss and a wince. It was just his luck that Merlin, whom he could never wake before the fifth time calling his name, somehow managed to fly awake and out of his room in panic at the noise.
"Gaius!" the boy exclaimed when he took in what was happening. "What on earth are you doing?" He moved forward to begin to pick up the the shattered remains of the glass at his mentor's feet, and Gaius wondered if it wasn't the only broken thing in the room.
On another day, when he was feeling stronger, he may have brushed the incident off, or grumbled at Merlin about treating him like an invalid. But tonight...tonight he was just so tired. And as he looked down at the tremor in hands that he couldn't completely quell, he just couldn't pull up the mask he was used to wearing. He didn't really notice when Merlin stared at him in concern, or when his apprentice tugged him over to sit on the patient's cot.
He would probably have remained off in his daze until sunrise if Merlin hadn't knelt in front of him and tentatively asked "Gaius?" Something about his tone vaguely reminded Gaius of a time long ago, on one of his visits to Hunith when Merlin was still a wee little thing and had gotten into one of his bags and broken something. Gaius had wanted to be angry, but the five-year-old was so sorry and repentant that he'd only sighed and let him off. Merlin had squeezed his eyes shut, holding the pieces of the eyeglass, and Gaius had reached out, thinking he was about to cry or injure himself on the broken glass. Before he could actually touch him, Merlin had opened his eyes with a shining grin and held the device up to him, completely intact. Shock had frozen Gaius in place, as he looked at this little boy, his deceased brother's grandson, who'd just done wordless magic to repair something whose workings he didn't know. Merlin, of course, didn't realise the enormity of the feat he'd just performed, and had beamed before he ran off when Gaius almost mechanically patted his head and thanked him. It was still sitting in a chest somewhere in his quarters.
Gaius blinked and refocused on the Merlin in front of him, looking very worried indeed, and his heart hurt.
"My dear boy," the old physician murmured, taking one of Merlin's hands into both his own. "You deserve so much more than the world we've left you with."
Merlin blinked, taken aback by this uncharacteristic display of sentimentality. "What are you talking about? You've already given me so much, and I really do appreciate it," Merlin rushed to reassure his mentor. "Honestly."
He tried not to be alarmed when Gaius' expression broke even further. For as long as Merlin had known him, he'd considered Gaius old. It was never a conscious thing - he was older than Merlin's mother and his hair had grey in it (when Merlin was younger; now it was all white), so he was old. It had never seemed relevant, even after Merlin got to Camelot, beyond knowing that Merlin had to run the errands because Gaius wasn't up to it. But in that moment, Gaius looked every one of his sixty-odd years.
"I'm so sorry it's taken something like this for me to see what Uther has become," Gaius said wearily. Understanding lit Merlin's eyes and then his entire expression shuttered, and he excused himself to go get something from the kitchens because Gaius had slept through dinner. Gaius let him go, making no mention of the covered plate that sat on the other end of the table. It saddened him to see his boy, the closest thing he'd ever have to a son, become so closed off at the mere mention of one of Gaius' oldest friends.
Although Arthur was constantly calling Merlin incompetent and complaining about any of the many faults he imagined Merlin had - none of which were true, Gaius could admit - his boy was far from an idiot. Gaius knew that Merlin was still (rightly) angry at Uther for having him tortured. He'd realised the depth of that anger completely by accident, the day he'd been released from the dungeons. He'd fallen into a sleep so deep and dreamless that he'd later wonder whether Merlin had drugged him, and hadn't woken up until sometime late that night. His shirt had been removed at some point so that Merlin could tend his injuries and although he felt cleaner than he had for his entire stay in the dungeons, his face was sticky, presumably with a salve for the bruising. Merlin hadn't yet realised that he was awake, as his back was turned so he could prod restlessly at the fire and mutter to himself.
"Decades," Merlin muttered to himself, giving the logs in the hearth a vicious jab. "Gaius has been with him longer than he's been king of anything and this is how he repays faithful service? One word from a glorified, overpaid, bounty-hunting mercenary and he condemns a sixty-year old man who's supposed to be a 'trusted friend'," it shouldn't have possible to put so much scorn into a single phrase, "to torture." Merlin's shoulders were pulled so tight that they brushed his ears, and his hair was standing on end like he'd been digging his hands through it for hours. He probably had. "And the Royal Butcher couldn't even be bothered to come check on the one person on the entire isle besides his prattish son who still cares whether or not he drowns in the blood of all the innocent people he's Slaughtered." He was well aware of some of the less charitable epithets Uther had garnered among the magical community. He'd never considered that Merlin may have seen his old friend in the same light.
Truthfully, the reality of everything he'd heard Merlin say before he let the boy know he was awake hadn't really hit him until a few days later. When his mind was more able to begin to process everything, he'd been so saddened by the realisation that Uther really was alone, despite being king. His allies were all wary of him, his subjects all feared him, all of magic hated him, and his magical ward grew more and more terrified of him each day. The king's entire situation was just, well, sad.
And then, out of the blue, a thought hit him like a runaway horse: none of that excused him. Like sparks catching on the kindling in a firepit, realisation after realisation flashed through his mind almost too quickly for him to keep up. Uther had chosen to focus on Ygraine's death rather than Arthur's birth and the entire kingdom had suffered ever since. Uther had never been a gracious loser. He'd gone and gambled with magic, thinking that he could dictate all the rules of the game, and had lost something he hadn't realised he was betting. But women died in childbirth everyday, and Ygraine's barrenness before the magical intervention may just have been her body knowing its own limits. For all they knew, Ygraine may have died anyway even if she were able to conceive naturally. But Uther had blamed magic, had fixated on Ygraine's death like he was the only man to ever lose a wife, and had thrown a glorified tantrum for a quarter of a century.
Torn as he was between fleeing for his own safety, trying to save as many as he could, and hoping that Uther would see reason and stop this madness, Gaius was the one who'd had to stand by and watch his friends flee or be killed, who'd had to stay behind and push the love of his life out of Camelot to keep her safe, who had watched helplessly as neighbours turned on each other for fear of their king, who had heard of mothers drowning their own children because of levitated toys, who had had to try to smuggle information to Druid camps so that a pacifist people wouldn't be slaughtered by their king. Eventually, he was the only fully trained physician left in the kingdom. He couldn't in good conscience leave them to the mercy of the next sweeping illness. And anyway, by that point, so many magical people had come to hate him for giving up his magic and staying 'safe' in the citadel (like he wasn't always one of the first suspects when anything went wrong), there was nowhere for him to go even if he did leave.
Gaius had given his life to Uther and his kingdom and his madness. He always looked at Merlin's risk-taking as the folly of youth and thought himself above such. How much worse was it that, as a grown man more than twice (and now three times) Merlin's age, he'd made excuses for standing by a king who murdered his own subjects for misdirected anger and guilt?
That isn't even in the realm of folly, Gaius, he thought to himself with a sneer. At least he was alone, so no one would see such an uncharacteristically vicious expression cross his face. It's idiocy.
He was aware enough to recognise why he'd let it go on so long - to admit that Uther was being ridiculous was to declare that all those lives lost were in vain, that it was in fact a senseless Slaughter and not a purifying Purge, that the friend he'd grown up with was lost to him and had been lost to him without him even realising when exactly 'Uther' had disappeared into 'Sire'. To admit that Uther was wrong was to be just as responsible for so many murders that the thought alone was suffocating.
But as horrific as the last twenty years of his life had been, he'd be insane to continue on as he had been. Uther would destroy his own kingdom with his ire, and it would be on Gaius' conscience because he'd seen the outcome from the beginning. He deserved better. Merlin deserved better.
So, for the first time in over twenty years, Gaius made a decision for the good of the kingdom over the good of the king. He'd been a young fool, and had grown into a right old idiot, but Gaius put his foot down at continuing into insanity.
However, business of this magnitude could not be undertaken alone. He had some old contacts to re-establish. In the meantime, he figured that tomorrow morning was as good a time as any for Merlin to take him herb-picking to help him recuperate from the witch finder's particular brand of cruelty. If the herbs were a bit more than mundane, and if Merlin happened to begin learning more than just healing from Gaius on this trip, well. That was just an old man who'd realised his mortality trying to pass on all his knowledge, wasn't it?
This is my idea of what it may have been like for Gaius to come to his senses after Uther had him tortured by the witchfinder. I explored Merlin's side of things, but Gaius deserved a (proper) response to his own torture on the orders of a man he had still considered a dear friend. I would have loved to see him wake up and decide to be the mentor Merlin needed, especially considering there really wasn't anyone else around who could have done it. Sadly, he spent the entire series postured as a wise voice of reason, but was actually instead one of the biggest hindrances to Merlin's development as a sorcerer.
Merlin loved him, and I do too, but he could have done SO. MUCH. BETTER.