If he had been at home (on Earth, which wasn't really home anymore but that's how he thought of it), he might have written her love letters. He'd never written them before; he'd never felt the inspiration, or else he hadn't thought they would be appreciated. But he loved Sha're as much as he loved words, and he wanted to find the perfect sentences to convey that. He wanted to write long, rambling notes that were about love because what is love if not putting time and effort and piece of yourself into showing that you care?
But he wasn't on Earth. He had only his journal to write in, and he would have run through all its blank pages in a week at best, and although he could speak Abydonian with an almost native fluency and read the stories in the pyramid, it wasn't yet his language. She had given those words to him, and what he wanted was to give her something that, unlike the freedom for her people, was just from him, and just for her.
He hadn't meant it as anything when he began scrawling Abydonian words in the sand one day. He was only practicing, writing and then erasing on the sand the way he would have used a chalkboard in the past. She watched him with a smile on her face; writing was still new to her, or at least being allowed to write. And then she read the words, said them out loud for no reason he could think of, but it made them mean something more than the dictionary definition (if the Abydonians had had dictionaries), and from then on he would write with her in mind. Some days, she would blush and smile at the sound of love, or happy, or free. Other days. she would laugh to discover that he had written goat, or hat, or stew.
Sometimes, after he started teaching her, he would write in English. She would carefully sound out the word, and then he would try to explain to her pizza, or car, or archaeology. And occasionally, when the mood struck him, he would write in another language, and it would be bonjour, or llamo, or obrigado and she would look at him shake her head and ask why he needed to know so many languages. He would smile and reply, "So I can say whatever I need to say to anyone." Then he would say, "I love you," because for all his dedication to the written word, some things were meant to be said aloud.