I give up.

1. Created Windows 10 boot media and Bootcamp drivers USB via Bootcamp.

2. Created Windows partition via Bootcamp.

3. System reboots to installs Windows and I get this:

4. Chose delete and format drive with same result.

5. Reboot into OS X and check disk utility and see this:

6. Reboot into Windows install again only for it to tell me it's not an NTFS partition.

What the heck is the deal? This is a late 2013 iMac with Fusion Drive.

All I want to do is run Brent into a wall.

Will give it a try.

So, what do the other drives look like behind that Windows dialog box?  Here is my understanding, that 200MB System drive is at the root of the fusion drive, which is not a physical drive but one that is more like a smart/intelligent RAID formed between the 128GB SSD and the 1TB magnetic drive.  Like with encrypted drives, where there is an unencrypted portion in the root drive that allows you to boot and then call up the encrypted portion, the fusion drive is supposed to have a system boot portion that comes up first before the fusion can be loaded.

You should be able to also see both your 500GB NTFS partition and the remaining 628GB on the HFS+ partition hiding under the dialog box.

Blew out the drive and reinstalled. OSX and Windows. Both working fine now. Now I need to figure out if migration assistant will break everything or not.

All is well.