Divinity 2: Developer's Cut Save Game Location

Windows

Divinity 2: Developer's Cut save games can be found on Windows here:

C:\Documents and Settings\\Local Settings\Application Data\Divinity 2\Savegames

Other Locations:

Divinity 2: Developer's Cut save games may also be found on Windows here:

Alt:

C:\Users\\AppData\Local\Divinity 2\Savegames

Linux

Divinity 2: Developer's Cut save games can be found on Linux (Proton) here:

~/.steam/steam/userdata/[user_id]/219780

Notes

You may need to set Windows Explorer to show hidden files and folders:
http://www.howtogeek.com/howto/windows-vista/show-hidden-files-and-folders-in-windows-vista/