His stomach drops somewhere into his boots (or his socks, since he's not wearing any boots at the moment) with an icy feeling running down his spine.

"I know you won't be what I had with Yen, Kate...I've always known that. I don't want what I had with her, I want t'make somethin' different with you. You ain't some...I ain't lookin' for someone t'replace what I lost, t'be the woman I used to be married to. That's never...you ain't some second-best replacement that I want just 'cause I can't have the woman I married the first time around, it ain't like that. I would never expect you to do that, and I'd never want you to."

He's being very serious - but at the same time, there's a quiet disbelief in the edges of his voice, simply because she was never a replacement for Yen - as he speaks.

Doc reaches for her hands.

"I want to be with you. Kate Barlow. For who you are."