Might be stuck in B5 (again) but i'll deal with it.
Okay so the game I just finished as I am writing this. I was a lucian 6/0 and I had a rek'sai support. The rek'sai in question did not buy a single ward, vision or stealth. I was the one buying those wards. The support in question also stole more then 80+ CS (even though you only need up to four with a full face of the mountain. The rek'sai also stole five of the kills, and not like those accidental last hit steals that a support will do everyone once an a while, no this Rek'sai stole five of my kills in front of my face.
In post game chat I told the rek'sai what he/she did wrong, he/she wouldn't listen and always talking in caps. It's stupid how people can think once they call a role they can build whatever the hell the want and call it a "support build" when it obviously isn't. Rek'sai support could work, if built a complete tank, with no damage what-so-ever. This summoner refused to listen to constructive criticism.
Personally I hope to never see that Rek'sai that was supporting me on the rift again, because I know that he/she will just troll and steal kills, and CS, and then call you a noob (that's what happened in post game) afterwards saying stuff like "MY FIVE KILLS SAY OTHERWISE", or, "i'LL REMEMBER TO FORGET TO REMEMBER WHAT YOU SAID" like really, if you're going to support then do it right, and that rek'ai was not doing it right.