The first was Blaine fucking Kurt with a vibrator and then talking dirty like "I'm gonna fuck you while you're still all strung out on the sensations" or something rather porn-y and smutty. found in comments!
The second is Kurt getting a "bunny" vibrator stuck inside him and blaine has to come along and get it out of him, all while getting kurt off at the same time. I believe this was on ff.net. found in comments!
The third is a kittyboy!kurt fic where Kurt's in heat and he and Blaine have sex and Kurt gives birth to actual cats! found in comments!
And the fourth is some sensation!kink fic with Blaine teasing Kurt and getting him off slowly.
Thanks in advance! :)