It's kind of funny. I have Fire Emblem Awakening, but I don't have a 3DS, so I've just been borrowing my brother's to play my game from time to time. And these rare playing times have led me to an odd conclusion. Even though the first two times I played through, I married Chrom, not only do I not really like that pairing, but out of all of my Robin ships, only one of them is het, and every other one is femmeslash. So I started with not my favorite woman, but the one who has the most open subtext no matter who they're married to.
Warning for creepy Tharja and possible OOC, since I'm still getting a grasp on the characters.
Possession or the five times Tharja made it clear Robin was hers
I was born to be the only one you'd love, don't you see, I'm your Pandora from above.
The first time that Tharja staked her claim towards those who would take Robin from her was the night after the Ylissean Exalt's death and the escape from the Mad King's grasp, when a few of the unsavory men in the army were outside her tactician's tent, talking about how Robin had been so brave to keep leading even after something so terrible had happened, and perhaps they should talk to Robin about how to be that strong.
She just couldn't have that, Robin was hers after all. Even if her object of obsession hadn't admitted (or realized) it yet, she simply couldn't share Robin with these ugly men. Clutching her nosferatu tome to her chest, she stalked up to the men gathered near Robin's tent and stood very close to them, glowering up at them with all the murderous intent she could muster.
They scattered very quickly after that, and she allowed herself a dark smile. No one would fight her on just who Robin belonged too. After all, she could quietly hex them all into misery and not one of them could put up a fight as to stop her.
The second time was to Chrom after they returned from successfully slaying one Mad King with the power of Robin's tactics, and he was trying to gently tell her that she didn't have to stay with the army anymore. Of course, she couldn't actually threaten him as well as she could the various men and women who seemed to like being around Robin, but she still laid out her point quite well for her.
"Your highness," she said darkly, refusing to address him by his technical title of Exalt until after he'd been properly crowned, "there's just one problem with me leaving the army if that's what you want me to do."
He lifted an eyebrow as she let the silence fill the space between them ominously, darkly. Then she smirked. "You see, Robin's mine. So if you want your precious tactician to stay, I will be staying as well. Or I could just hex you into letting me take Robin away with me."
Chrom sighed and looked like he wanted to put his head in his hands. "Very well...then you can stay," he said, not sounding like he wanted to say it, but that he had no choice.
Tharja allowed herself a small smirk. Just because she wasn't allowed to bring her cursing implements into a conference with the Exalt to be didn't mean that she couldn't get her way.
The third time was to a foolish nobleman in Ylisse. He had somehow gotten the idea that Robin was available and that he was any sort of option to the noble tactician. Thus he had been subtly trying to hint to Tharja that her protectiveness over her beloved tactician was unnecessary and unwanted. It hadn't worked at all.
So one day he cornered her in a hallway in the castle when she had left to let Robin work in peace at planning out army strategies for Chrom's coronation, and Tharja wrinkled her nose in disgust as his awful perfume washed over her nose. Couldn't the man wear something that didn't smell like a flower slowly decaying into Risen? All it could make her think of was fighting Risen alongside Robin, which while not the worst memory, was terribly distracting when being bothered by this fop of a count.
He loomed over her, which only had the effect of getting his falsely red curls to hang in her face, and exhaled a breath that stunk of his appalling lunch onto her face. "Ah, the Plegian dark mage," he said in a taunting whisper, "I believe we have had several conversations as to whether or not you should be bothering dear Robin so. So why do you continue to persist? You are merely a hindrance to our love."
Tharja rolled her eyes at the ridiculous man. "I should be saying that. It's not me who's bothering my Robin, it's you. Robin doesn't want anything to do with you."
The count glared at her, but he had nothing on her for chilling death glares. "We will see who our Exalt believes is more necessary after his coronation. And if Chrom is at all smart, he'll send you back to Plegia in chains." and with the empty threat, he swept off in a flurry of silk robes and awful perfume.
Tharja could only smirk evilly at his back. Her curse would take effect that night and soon he would find himself increasingly unable to be near her Robin without feeling ill. After all, Robin would never love a man who vomited every time he got close.
The fourth time was a lovestricken young girl who Robin had personally rescued during a bandit attack at quite painful cost, taking a hard blow to the shoulder that nearly bled out before Tharja found a healer, and this was the only of Robin's suitors that she felt any sympathy towards. For one thing, she simply wasn't a threat in a way that any of the others had been. Two, she was far too painfully shy to even say anything to Robin.
That didn't mean that she liked being in the position of watching the girl weeping in front of her after she told her just who Robin belonged to and how she had no chance. Biting her lip to keep from saying something harsher, she considered how Robin might phrase it and said "Just because Robin is perfect doesn't mean that there's not someone out there you'll like more. And crying over Robin all the time will prevent you from going off to find anyone else."
The girl sniffled and wiped at her eyes. "Why are you being so nice to me?" she said thickly, snot bubbling out of one nostril. "You're the mage who's hexed everyone else away."
Tharja was faintly regretting that kindness as she said "Well I was less secure then. Now that I know that Robin will never leave me, all I need to do is intervene before someone actively tries to get in the way." And really the girl reminded her of Robin in some ways, namely the hair color and length, and that was probably why she was actively trying to be nice to her. "But you're young and pretty and you'll find someone else who you actually like. I've heard that the Exalt is looking for a bride himself."
The girl sniffled and wiped the snot away from her nose. "Wh-you think the Exalt himself would like me?" her eyes went as wide as coins as she stared at Tharja.
She considered the possibility and concluded that even if he didn't just yet, she could make it so and then he would be less of a threat himself. "Why not?" she said, already trying to think of where she could get the ingredients needed for a love potion quickly, "Even though you can't have Robin, that's no reason to think that no one else might like you."
The fifth time was to Robin herself, late in their bedchambers a year after what everyone was calling the Mad King's war. Tharja had been playing with a strand of her hair as they lay in bed, with only the faintest sheen of light from the sickle moon shining in the window and making her eyes glow the deepest finest shade of brown. Despite the relative comfort of the situation, she could tell that Robin was nervous about something. But a year had taught her not to push, because otherwise Robin would clam up.
As she gently twisted the lock of hair around her finger, Robin finally said "Tharja...why me?" in a quiet voice that barely disturbed the otherwise quiet of their room. "What made me so special that you chose me above everyone else?"
Tharja had been quite shocked to learn before that Robin could be as insecure as anyone else when she truly let down her guard, but now she valued and adored that trait because only she got to see it. Touching her cheek, she said "Because you are the woman I have looked for since I knew I was searching for someone. I saw you in battle and knew I would follow you anywhere, obey you no matter what, and curse anyone who got between us." She brushed her thumb over Robin's perfect lips. "You are mine, Robin, mine and no one else's. So don't worry about why because it doesn't matter. All that matters is that you are mine and I am yours."
She felt Robin's lips curve into a smile and the other woman shifted closer to her, the warmth of her body luring Tharja into her never malicious but always effective trap. "I didn't think that I would love you when I first met you," she said, her breath caressing Tharja's cheek with the sweet words, "but I wouldn't give up what you've shown me for anything."
There was no way she could respond with anything that explained or held that sweetness back, so she simply kissed Robin and let the night see them as they were meant to be.