PostFragment.kt

class PostFragment : Fragment() {

    private lateinit var bin: CompositeDisposable
    private lateinit var vm: PostViewModel

    private lateinit var id: String

    private lateinit var title: TextView
    private lateinit var body: TextView
    private lateinit var refreshButton: Button

    // Kotlin's extension methods can provide syntactic sugar
    fun Disposable.into(bin: CompositeDisposable) {
        bin.add(this)
    }

    override fun onViewCreated(view: View?, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        bin = CompositeDisposable()
        
        vm.content(id)
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe { data ->
                    title.text = data.title
                    body.text = data.body
                }.into(bin)

        vm.refreshClicks(RxView.clicks(refreshButton))
                .subscribe()
                .into(bin)

    }

    override fun onDestroyView() {
        super.onDestroyView()
        bin.dispose()
    }
}

PostRepository.kt

interface PostRepository {
    fun loadPost(id: String): Observable<Post>
}

PostViewModel.kt

class PostViewModel {

    private lateinit var refreshRequests: PublishSubject<Boolean>
    private lateinit var repo: PostRepository

    fun content(id: String): Observable<PostViewState> {
        return Observable.just(true)
                .mergeWith(refreshRequests)// Merge with subject to trigger a refresh.
                .observeOn(Schedulers.io())
                .switchMap { repo.loadPost(id) }
                .map { post -> PostViewState(post.title, post.content) }

    }

    // You could substitute this for any input type. Clicks/Pulls to refresh, Event a timed interval.
    fun refreshClicks(requests: Observable<out Any>): Observable<out Any> {
        return requests.doOnNext { refreshRequests.onNext(true) }
    }
}

PostViewState.kt

data class PostViewState(val title: String,
                         val body: String)