Found in the comments
Hey everybody. I'm looking for a fic, but the things I remember all fall under the 'I think' category, so googling for it has been a pain. The premise is that Dean and Cas have been together for a while and Sam totally notices they are acting strange but doesn't catch on.

• I think it was a 5 times type of fic, aka 5 times Sam caught Dean and Cas and one time he caught on.
• I think he caught on when sex pollen was involved and Dean and Cas were all, well that's no problem, we'll take care of it (I think it was Cas that was hit it with it, but it could have been Dean)
• Cas was all 'Dean I thought you told him', and Dean was convinced Sam knew, because Sam caught them showering together.

I hope someone can help me with this, it drives me crazy when I fondly remember a fic and then can't find it anymore.

Other DeanCas fic where Sam is oblivious is always welcome, or DeanCas fic from Sams POV and him being awesome :)