Ash Redfern: Soulmate Link
Ash, as an upstanding member of the Night World, no more believed in the soulmate connection than he did in James Rasmussen actually being a transvestite werewolf. He makes it clear in Secret Vampire that he does not believe in soulmates and thinks that those who do are... 'touched'. At the end of the first book, James tells Ash that one day he will care about someone and it will hurt. Daughters of Darkness tells the story of Ash learning to care about someone and the pain it causes him.
When he first feels the connection, Ash reacts negatively. He is described as looking "like a cat who's had a shock. Bristling. Unhappy." We later learn that he recognised what had happened immediately, but he says nothing at the time. Like Mary-Lynnette, Ash fights the connection, but he fights it for very different reasons. The discovery of his soulmate started a chain reaction, bringing down the defenses Ash had been building since childhood. The connection stripped him down to his 'true' self (see hiding behind a facade?), leading him to question everything about himself.
He tries, unsuccessfully, to ignore the connection. He acknowledges that it's there, but refuses to let it dictate his actions. He blames the whole thing on his defective "Redfern genes" and tries to set it aside even though his thoughts run along the following lines:
himself... could he lose that in five minutes?
... No, he concluded grimly. Absolutely not.
Not in five minutes. It only took five seconds.
(DoD, page 82)
When he and Mary-Lynnette are revealed to the Redfern sisters as soulmates, Ash tries to cover his own back. He suggests that they all go home and agree that Briar Creek never happened. This is supposedly to safeguard them, and that probably was part of his reason for suggesting it. However, agreeing that Briar Creek never happened would allow Ash to pretend that he never found his soulmate, thus protecting him from the Night World (he has broken their rules after all).
Even when he is supposedly "ignoring" the situation, the effects of the soulmate connection are visible. Ash's quest to prove to Mary-Lynnette into a vampire as part of a plan to save his sisters, Mary-Lynnette verbally attacks him, demanding to know why she should give up everything so that his sisters can be happy. What she doesn't realise is that Ash wants to turn her into a vampire so that he can be happy. At the end of the book, Ash has changed a lot but he is still, fundamentally, a Night World vampire. He is finding it difficult to let go of certain things and sees that it would be better for him if his soulmate was a vampire, rather than a human. Perhaps he is looking for someone to share everything with him, but it is partly because he can't let go of everything he has believed in for so long.