It was a partnership forged on a cornerstone of necessity, when the need for protection and a reinforcement of power was worth more than the respect of the Council; worth more than the lives of those few she had still called family. It was the decision of a moment, a scared little girl scrambling for something that seemed like hope, only to have it dashed against the rocks once again. And then it had happened. And then he had come alive again.
The partnership was formed at that moment, though tentatively, and she had often reflected that if she had an ounce of sanity she would have left him in that room then, and it would have been the end of it. Granted, she would probably be dead now, but she wouldn't have to deal with so many annoyances, would she?
The partnership was one that sprung from a bond of very tentative trust, and the double-edged sword of needing each other. She needed him, for without him, she had no way of assuring herself the power that she needed to run the Hellsing Organization – she couldn't do it on her own. He needed her, for some kind of direction in an endless life; he enjoyed chaos, but it was his curse and his blessing at once, that he should be required to serve whomever was the master of the Hellsing Organization and carried the blood of their family, upon his awakening. Those were the bonds – nay, chains – that held them to one another, the mutual necessity that ensured their loyalties.
She kept him from going off, from hurting others needlessly, as he would have done if not for her influence. She kept him from finding for himself the kind of monster that he could be, if she took her hand from the leash. She allowed his monstrosities in small doses, where it was necessary, where it was safe. Where the massacre could be justified, and she tried to rein him in from anything beyond that, though it was sometimes "hit or miss" on that level.
He kept her honest; he kept her pure. He kept her from either falling apart in his hands, or becoming a puppet manipulated by the strings of the council and her conscience. He kept her sharp, testing the blade of her wit and her conviction against his own just often enough to annoy her, to corral her into thinking of new ideas, to force her to think of new and innovative plots to get around his own.
They had a mutual need for one another. She kept him tied back with her strings, and he kept her from becoming tangled in them.
It was more than just an arrangement.