The point of this story? To force Castle to show a different side to himself very quickly, and make Beckett realize that there is more to her favorite author than what he appears to be like in the media and how he acted when they first met. She's far more impressed with Richard Castle the Father than she is with Richard Castle the Playboy.
Now where can this story go? I have no idea. I don't know what I want for it, other than a chance to have the man show off his better qualities early on. Other than a chance for he and Kate to get together sooner, I don't know what else this story would entail.
Oh, also, to rehash something from an older idea, the one where Rick and Kate meet while she's still attending college at Stanford, the idea is that she began Stanford a year early, meaning she turns 18 while there, and meets Rick in a park while studying that Spring. They get to talking and Kate offers to watch Alexis for him on nights that he can't be home, which is a pretty good arrangement. Let's say it's April when this starts, as time goes on, Rick starts thinking about moving back to New York, to the loft that he already owns, but hasn't put that plan into action yet; when Kate gets back from New York she shuts him out entirely and he winds up calling her dad to ask what's going on, and that call interrupted Jim's binge and made him wake up to what he was about to do. Jim asks to speak to Kate, and this gets her to open her door, and he winds up talking Kate around to opening up to Rick; it turns out Rick just saved his life by making him realize he was about to throw it all away by crawling into the bottom of a bottle.
And that's about all I have left right now. There's more, like the fact that both of them move back to New York, so the arrangement hasn't changed all that much, and Jim doesn't become an alcoholic, so Kate has a much bigger support system from the get go. How I'm going to ply this story into one where Kate and Rick get together, I don't know; it'll happen, though, and much earlier on than canon, that's for sure...