WHAT? I mean, this is sooo perfectly written, but... WHAT?
I love the way the story flows here. How we don't know what happened, just that included some kind of a blade and that Kate was hurt. Since you wrote that thing in the summary, I'm guessing she's not dead but maybe in a coma or something?
I really want to know what happened.
He even trained to get stronger and faster so he could catch the killer? Does that mean that person is not in jail or?
Ah, SO many questions.
You portrayed his angst and horrible state he's in wonderfully. A reader can feel what he's going through. I almost started crying. Oh, man, this is good.
Can't wait for the next chapter!

OMG broken halo indeed. I don't know if I could watch or read Castle actually kill someone but I would still love another chapter or two. I suppose he did beat up a guy just for aiming at Kate so logically the next step would be killing so I can't wait.

Please tell me she isn't really dead.

That was Amazing!

Haven't really seen a Castle this dark other than a little in Knockdown when beats up Lockwood. You can see how much he wanted to protect Kate. So to have it happen after they where together would kill him so could see him going down the rabbit hole. Can't imagine the mental shape he would be in after months of Kate being gone.

The descriptions made his pain feel so real. He doesn't give up once he sets his mind on something so getting in shape makes sense for what he plans to do.

Even though leery of the angst curious where going with this.

OMG what are you doing to us, what?! Unnfgggghdhdd. I am truuuusting you to fix this, mkay?! Good. This is so dark and raw and real; and oh, the writing so good, such pretty language... stab me in the heart, why don't you?!

Whoa. Dark and dangerous and utterly heartbreaking. Well done.

OHMYGAWD HOLLY. The couple last scenes there. Holyshiip, it got me breathless! OHMY OH MY OH MY LAWDDD, THIS IS GOOOODDDDD! AJKKGAJGMAJ I CAN'T WAIT FOR NEXT CHAPTER!

:DDd

I cannot wait to see what happens with this one!