They just got dressed when he says it.
"We'll get our breakfast, then we'll visit Lannisport, my beauty." His tone is casual, as if it's a blatant fact that just goes unsaid because it's unnecessary to be stated all the time.
She freezes. Conveniently, she's in front of a mirror, the very object that's always told her the exact opposite of what Jaime just said so nonchalantly. How can he call her 'his beauty', when she looks like she does?
She hears his voice. "Brienne, my love?" She turns to see him with a concerned face. "What happened? Did I say something wrong?"
She hangs her head low. "You don't need to sweet talk to me, Jaime," she says quietly. "I know you married me for love. You don't need to pretend I'm beautiful."
Before she realizes it, his arms are around her. She raises her head to see him in front of her, blocking her view of the mirror. "What makes you think I'm pretending?" He asks with a pained voice.
She hates to cause him pain, but she doesn't understand why her words hurt him. She's freeing him from the pressure of reassuring her of something that isn't true, after all. "I'm ugly," she replies. "That's a fact I've dealt with my whole life, and the battles were not kind to me. I learned to live with it, to accept it, but it doesn't make it any less true. You even said it when we first met. I know you love the woman underneath this ugliness, but neither of us can run from it. So I'd rather you didn't try."
He sighs. His left arm leaves her waist to hold her hand and guide her to the bed. When they both sit, he cups her cheek and places a chaste peck on her lips. "Let me tell you, then," he whispers against her mouth, "how it was to fall in love with you."
She blinks in surprise. This is not what she expected him to say. He breaks what remains of their embrace and rests his stump on his lap, while his hand leaves her cheek and grabs hers once again. "Do you remember my answer when you asked when I fell for you?"
"You said it was a slow process," she replies, remembering the words that made her insides melt at the time. "It began in Harrenhal and culminated with Stoneheart."
He hums. "Exactly." He kisses her knuckles, then brings their hands to his lap. "Yes, I found you ugly when we met, although I always thought your eyes were pretty." He takes a deep breath. "The first change was about your hair. What I once deemed plain and messy became… cute. A redeeming feature. It suited you. It still does, even if it's a bit longer now." His hand leaves her and catches a straw, tucking it behind her ear. "I like it as well. It remarks on your 'secret Targaryen' aura."
She chuckles. She learned her hidden heritage by accident during the Long Night. For a whole day, she was afraid to tell Jaime about it, aware of his general uneasiness towards Targaryens, but the fear of him finding out through someone else won over. Her anxieties proved unfounded when he chuckled, japed that maybe she could ride a dragon and kissed her.
Oblivious to her reminiscing, he goes on. "When I saw you naked in Harrenhal, I…" He blushes. It's adorable, even more because it so seldom happens. "Gods, this is embarrassing, but it must be said. I was ridiculously attracted to your hair… down there."
She blinks. "Did you see it—oh. I stood up for a few moments."
He chuckles, still blushing. "Enough time for me to appreciate what I saw and remember it for the longest time." He grabs her hand again. "Then it was your freckles. When we were on our way to King's Landing, I found myself counting them. By the time we arrived, I was mentally comparing them to constellations."
As if to emphasize his point, he kisses a spot on her left cheek that must be at least one freckle. His beard tickles, and she giggles. "I love your laugh," he says when he retreats. "And, while at first your teeth bothered me, when you first smiled within my sight I was so besotted I could only think no one else could smile that beautifully. I thought your teeth were unique, and so undeniably yours I couldn't help but love them. But that was later.
"When we were in the White Sword Tower, and you showed your trust in me, your belief that I was a good man… your eyes turned from 'pretty' to 'astonishing'. Your twice-broken nose grew appealing. Then… you were wearing the dress I had made for you, and—that was when I first noticed your breasts drew curves on your sides." His gaze drops to her chest. "I thought of these curves many times after you left. Cersei stood naked in front of me, and all I could was, 'those curves are too obvious'." The intensity of his fixed stare takes her breath away, until he raises it back to her eyes. "I like that yours are subtle. It adds an air of mystery. I love that I have to pay attention to find your curves. It feels like I earned them, like I earned the right to find your beauty because you feel safe enough with me to let my eyes linger on your body."
He's right. If any other man stared at her, she'd punch him or run away from him. Jaime's gaze is different though. When he looks at her, she doesn't feel like trash or a piece of meat; she feels like a woman worthy of love and desire. She lets him look because she knows he doesn't take her permission for granted. He treasures it, he treasures her, and it means everything.
"When you stood between me and Lady Stoneheart, I found it appealing that you were taller, broader and as muscular as I am, because it meant I was safe. It probably doesn't sound all that manly, and I'd never think I'd enjoy finding safety in someone else until I met you." He goes forward to kiss her scarred cheek. "I like to lift my head and stand on my toes when I want to kiss you. It's… it's the same feeling about your curves. I like that I have to make an effort—that the right to kiss you must be earned."
She really wants to believe him, but… "I still have scars," she argues. "Large and disfiguring ones, like the one you just kissed. It's impossible to find beauty in them."
He recoils, as if slapped. "It is absolutely possible," he says passionately. "When you showed up in my tent in Pennytree, all bandaged and tired and looking older than your twenty years, all I could think of was your state of health. After we fled Stoneheart's camp to fetch Sansa, and you fell ill halfway through—" He shudders. "You know you nearly died out of infection on this cheek due to what Biter did. You know I married you in the Quiet Isle because I refused to part from you when you were at such a big risk of dying from your wounds. Brienne, the fact that you survived makes your scar stunning in my eyes. Every scar you carry is a reminder that you survived whatever perils you faced to get them. How could I ever find them ugly when the alternative was losing you?"
By now both have tears running down their cheeks, although probably for different reasons. "Although I wish you didn't have these scars," he continues, "it's not for the reasons you do. While you wish it because you find them irredeemably horrendous, I wish it because it'd spare you the suffering that got you them. But none of them lowers my opinion of your beauty."
She blinks, letting her tears fall. Jaime never lied to her, not even as a payback when she lied to him about Sansa. He wouldn't lie to her now of all times. He truly finds her beautiful, even the parts of her she hates the most. He didn't learn to love her despite her flaws; they faded away as he fell for her.
He pulls her down for a hug, his hand caressing her scalp as cries over his shoulder. "I love you, my beauty," he whispers. "I wish you could see yourself as I see you, but I have the rest of my life to prove the truth of my words and feelings to you."
"I believe you," she whispers back. "I truly do, Jaime. And I love you even more for it."
He breaks their hug to kiss her, slowly and carefully, in a way that tells her she's precious to him. When they part for air, he smiles. "Now that this matter is settled, my pretty lady, let's go break our fast so I can give you a tour around Lannisport. I know the city will make your eyes light up in that beautiful way that leaves me breathless, so I'm looking forward to it."
She smiles back.