When she accepted the deal - the marriage - she had more ideas in her mind that the ones she had been able to turn into plans. She had long ago forgotten those childish dreams about love and innocence so she deemed fitting to be married to a man she didn't love once again - and this time she wouldn't fall in love. This time, she would use the man like Viserys had taught her.
Eddard Stark might had thought he was doing a favor to her and keeping his honor like the stupid man he was - one who respected honor and family like no other in the Seven Kingdoms and across the Narrow Sea. He had thought that by keeping her under his eyes after the Usurper's death, she wouldn't try to regain her rightful place in the throne. She was barely more than a child for them after all.
He had sent a man to offer her a safe return, to be placed under his protection and by that he meant to be turned into his eldest son's wife. He wanted for her to be sent far into the North in Winterfell's Great Keep - to keep her a prisoner.
But she trusted in her capabilities and also that no man proud of calling himself so was able to resist a woman if she knew how to make him see what she wanted him to see. Even a Stark could be turned into her ally if she picked her weapons wisely.
Her only demand had to bring Ser Jorah Mormont back with her but he was the one refusing to such thing. So she only would have Irri, Jhiqui and Doreah with her. Her babies - her dragons - were not part of the deal but she took them with her anyway.
She was not afraid of Robb Stark - she had been married to Khal Drogo and, no matter how poorly they talked about northmen, she doubted it could be much worse than the nomad's life.