Two recs - K/Mc, K/S/Mc

[syredronning]

Beautiful, angsty Kirk/McCoy moving towards Kirk/McCoy/Spock story (with happy ending, thankfully!)
"Rearrange"
https://archiveofourown.org/works/8836918

And a "Trektober2019" collection with Kirk/McCoy, many great shorts with some scorchingly hot MU stuff insides
https://archiveofourown.org/series/1508747