This is a response to a anonymous prompt from 25/April/2014: "RobertxLyanna. AU would be Lyanna being alive after the war was won."
When Robert had gotten the raven saying Ned had found Lyanna, he had wanted to leave the Red Keep and make his way to Dorne, but Jon stopped him.
But Robert still met them halfway, with just one member of his new Kingsguard, waiting for them at the inn, he could only see three horses - he knew Ned had ride out in a company of seven, and worst was that he had riden out mad at Robert, what could he say to the Lannisters? He wouldn't have been able to hurt those children himself, but he couldn't lie and say that it didn't made him feel better after what Rhaegar did to Lyanna.
When they were finally there, Robert immediately made his way to Lyanna, wanting to make sure she was really alive, but he noticed she held something else… or someone else, and he knew that his fears of rape were true.
"The bastard raped you, my lady!" He yelled, wanting to kill him again… and again…
"Your Grace," he heard Ned say, but his brain didn't ackowlegde it, and he was furious, wanting to hit something, when Ned came closer held him, and called him for his birth name. "Robert, calm down, you need to hear Lyanna out."
He finally listened to Ned, and led them inside, and followed Lyanna to her chamber, where she started by feeding the baby, surprising the babe didn't have any Targaryen traces - if he didn't know Ned so well, he would say the kid was his.
"Are you hurt, Lya?" Robert asked from the door, trying to stay calm.
"I'm not, Your Grace."
"Gods! Don't call me Your Grace, I'm to be your husband, just call me Robert."
"I'm not a maiden anymore, Robert."
"The bastard raped you, Lya, if you think I hold that against you… it's…" but she stopped and while she burped the baby, she said.
"He didn't, Robert. I never meant to be this way, but I left with him in my free will." Why?! It never had gone through Robert's mind that she may had wanted to leave.
"Why?! Did you love the bastard?" He asked with venon - spiting between his question - but with a feel of sadness as well.
"I thought so, but soon learned I didn't. I was just a play in a bigger game, he only needed a child." She said hugging the child to her arms, and he knew she wouldn't give the dragonspawn away. "I heard you killed his siblings."
"It wasn't me."
"But you didn't stop them," she said with the same eyes that Ned had told him a moon before.
"Come back with me, I can make you Queen." Robert promised her.
"What would happen to my son then? If you knew me at all, you would know I would never want to be Queen." And if you knew me you would no I would never want to be King. "No, Your Grace. I'm getting on a ship to the Free Cities, and start fresh there. I'll be dead to Westeros."
Robert spent the entire ride to the nearest harbor, trying to convince her to stay, to give them a chance, promising her everything she wanted, ignoring the whores that threw themselves at him at inns - but no avail, and he still saw her sail away, to a new adventure.
Getting back to King's Landing was awful, it meant dealing with the future, and his upcoming marriage to the Lannister girl - she was beautiful, and by convencional ideals probably more beautiful than Lyanna, but to him she couldn't even be compared to his Lyanna - and he was alone, just him and Jon Arryn, while Ned rode home, to his new son.
It was a fortnight before the Royal Wedding when Robert knew he couldn't stay, his dreams were filled with images of Lyanna - even the few brothels he visited or the wine and ale he drank couldn't erase her - and boys with black hair and blue eyes, and sometimes her own boy - Robert knew that loving a boy with Ned's face and Jon Arryn's name couldn't be that hard, especially if he was doing it for her.
So a fortnight before the Royal Wedding, Robert boarded a ship to Pentos - the same city Lyanna had gone too - and maybe he would find her and convince her to love him too. While he left the Seven Kingdoms in the hands of whoever wanted it.
