Apologies for all the angst and confusion, hopefully this will clear some of it up. Poor boys, I'm cruel to them. Also, I'm uploading this at 20 to 7 in the morning and put it this way: I'm not up early. So if there are mistakes, I'm sorry, and I'll fix them when I'm awake. Enjoy!

Disclaimer: None of this is mine.

"Tell me why." He sounded so completely broken, even the coldest heart couldn't have stood for it.

Bertrand reached for his lover's hand, but Robin stepped backwards, out of reach.
"Robin-"
"No, Bertrand, just tell me. If love is all we need, why the fog are you so dead-set on drinking poison? Don't you-?" He was startled by the sudden stabbing pain in his cold, dead heart as he realised what the breather was asking.
"Don't ask me that, Robin, don't you dare."
"Then tell me why you kept this from me."

Bertrand took a deep, unnecessary breath.
"I knew if I told you, you'd stop looking for other options. Obviously, I was hoping for something less dangerous, but if that's what it takes to protect you, Robin-" The boy shook his head, still confused.
"But you don't need to. If you love me, I won't become loyal anyway."
"We need to be careful, I can't risk you. I won't."
"So you're saying it won't work. This... it won't protect me, without the potion?"
"I don't know." Bertrand closed his eyes and waited for the inevitable accusation. Robin didn't disappoint.
"You don't know if you love me?" He hesitated for a second too long before replying, and Robin continued. "After six years, after all this-?"

"Vampires don't love." When he opened his eyes, Robin looked as if he'd just been slapped. "Vampires can't love. Everyone knows that."
"You can. Vlad loves Erin, and you..." He trailed off uncertainly, and Bertrand stepped closer, relieved when Robin didn't resist him putting his hand on his cheek.
"I love you. I do. Look at me, Robin, I'm telling the truth." He didn't know how to explain his fears, but he had to try. "I... I love you as much as it's possible to love anyone. That's why I need to take the potion, it's why I'm doing all of this."

Robin was trying to understand, really he was, but Bertrand wasn't making any sense. He picked up the book and showed it to him, wondering if perhaps one of them had misread it. No, there it was, clear as a moonlit night. '...physically incapable of conferring loyalty upon him through fangs on flesh.' Bertrand glanced down, but he too seemed unsurprised by the contents of the page.
"I know what it says."
"Then you see? It's gonna be fine, you... you could bite me now and it would be alright, you don't have to worry." He was still annoyed that his lover had kept this quiet, but Bertrand was secretive by nature, and he'd obviously been wrestling with it – he could let it pass, at least for now, if only the vampire would accept that this was the solution, not some old poison. "You don't have to hurt yourself."
"I'm not biting you without that potion."

Robin knew he could have a temper; it had always been one of his flaws. Now, it flared up as it rarely did around Bertrand.
"That's it? No discussion? You're not even going to ask me if it's OK, you're just going to poison yourself for no apparent reason?"
"Robin-"
"Have you even thought about what it'd be like if it went wrong, how miserable you'd be?"
"Bran-"
"Don't you 'Bran' me, Bertrand, it won't-"
"Let me explain. Please." His voice was quiet, resigned, and it was that more than anything that brought Robin's voice back down to a reasonable level. Besides, if Bertrand was using his pet name – especially outside of their own house – he must be in the grip of some very strong emotions indeed. Bertrand never called him Bran except in extremely special circumstances. He folded his arms crossly, leaning back to perch on the edge of the nearest table.
"This had better be good."

Bertrand took a moment to gather himself, and Robin could feel himself growing impatient again. He couldn't imagine how Bertrand could possibly justify his actions.
"Vampires can't love, it's just... that's a fact, as far as the world is concerned. So how can a vampire's love save you? It's like saying unicorn blood can cure chickenpox... maybe it's true, but even if you find a unicorn and try it, how can you trust that the person who wrote it knew what they were talking about?" Robin frowned. The vampire still wasn't making a lot of sense.
"What are you saying?"
"What if... what if they're right, what if I can't love you enough to negate the loyalty? You know I'm not a nice person, Robin, the things I've done... What if my love isn't good enough?"

Bertrand backed up a little until he could sink into an armchair and curl into himself, forlorn and vulnerable, eyes fixed on Robin's. He was surprised to see tears welling within them; he could count the number of times he'd seen Bertrand cry on one hand and still have fingers spare to count something else. He stared at his boyfriend for a few minutes, trying to work out what had just happened and how he was supposed to feel about it, before it became apparent that Bertrand wasn't going to move. His head had dropped onto the folded arms he'd curled around his knees, and it seemed like he'd completely shut down.

Robin reached a decision and stood.

Bertrand couldn't bear to look at Robin, unable to stand his own weakness. He'd borne it so well, the uncertainty, the knowledge that he couldn't protect his beloved Robin the way he wanted to, and he'd found a way to do it. He'd tried so hard, and now Robin was refusing his protection, and ever since the breather had decided it was time it seemed as if everything was falling apart. They hadn't even resolved their last fight yet and here they were having another. He couldn't deal with this, this private debate in a space that was not their own; he couldn't cope with the broken sound of Robin's voice, he couldn't handle the accusations and the guilt. He simply lowered his head and hoped that at least whatever Robin did now would be over quickly. Shouting, crying, even just opening the curtains – he didn't care as long as Robin did it before he could completely go to pieces.

The hand in his hair, then, surprised him as it came out of nowhere and began to stroke gently. He tensed, waiting for some other reaction, but then Robin's voice was in his ear.
"It's been way too long since I got to call you an idiot." He lifted his head slightly to peer over his arm at Robin, who was gazing back at him with tears in his own eyes. They stared at each other for a long moment, the breather still stroking the vampire's hair, and then Robin spoke again. "Idiot."

Bertrand frowned, trying not to be hurt by the word, but his lover leant in and pressed a kiss to his temple.
"Of course your love is good enough, B, there's no love stronger. Look at what you're prepared to do to keep me safe."
"You've changed your tune." He wasn't very good at expressing relief.
"Someone amazing opened my eyes." Robin smiled dopily at him before his expression hardened. "You're still not drinking that stuff, but I understand now."
"If you understood, you'd know I have to-"
"Bertrand du Fortunesa, if you so much as make that poison, or buy it, or sniff it, I will leave and never come back." He hung his head.
"You'd be alive." Robin let out a growl of frustration and went for his neck; from anyone else it would be a threat, but Robin just wanted to remind them both that Bertrand was his, to mark and keep forever. The first nip was gentle enough.
"I'd be miserable." Then he began raising bruises in earnest, teeth pressing firmly into Bertrand's skin.

He wasn't sure if he was forgiven or not, if they were okay – he was vaguely aware that he himself had been cross with Robin not so very long ago, though he couldn't remember why – but he couldn't help but uncurl his body from the hunched position he'd been in. Robin pulled back and smiled at him, mission accomplished.
"I love you, Bran." He never wanted to give Robin reason to doubt it ever again.
"Love you too, B... But you know the pet name's not just going to get you out of trouble all the time, right?" He sat down and snuggled into Bertrand on the big, squishy armchair. "And I hope you weren't planning on moving any time soon, 'cos that's not happening."
"We're in Vlad's library, we can't just sit around being all... loved-up." Robin raised his head and grinned at him.
"Ah, but Vlad thinks we're fighting, he won't come in here for hours." He nuzzled back into Bertrand's neck – the unbruised side – and sighed contentedly. "You're all mine, du Fortunesa."

Bertrand smiled at him fondly. He could cope with that.