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Sometimes what she likes best are the simple things.
Like when Han and her are at a dinner party with Luke and Mara (sometimes accompanied by Wedge and his current girl, and even on rare occasions Lando and a gang of crooks), and they're all at once talking over each other in a booth at some shady hotspot in Coruscant and she feels Han's warm arm draped casually over her shoulder. She feels happy, simply content, nestled into his side, the pads of his fingers gently brushing her shoulder or the back of her neck. They tighten occasionally when he's talking or leaning over her to grab something, definitely if another man makes a leer at her, and she smiles and laughs silently because of it.
Sometimes, it's the subtle things she likes best. Like on those rare occasions when they both return home after a long day's work at the same time and he holds her before kissing her into a puddle. Then he reaches over and opens the doors and he always, always lets her go in first. This is because as much as he wants to be rough around the edges (which he is) he is foremost a gentlemen.
Or, and here's something she loves infinitely more, when he wakes up first and stares at her in the pale sunlight. This is something Leia knows he does because she can sense it before waking. If she wants to, she can take a long time to wake. It is so nice to be looked at in the morning light because that's when you know that it's real.
And, of course, there are the big, truly significant things she likes. Like him staying, and loving her, and accepting her, and did she mention loving?
More often than not, she is glad to be his.