Hidan first appears at the end of Naruto Shippūden Episode 71: My Friend, but you can see a static-y version of Hidan in earlier Shippūden when the Akatsuki are taking out the One-Tails, Shukaku, out of Gaara. Beyond that you get flashbacks of him but I don't know which episodes those are.
The two share a kiss, but Mavis dies from the effects of their shared curse, leaving Zeref to cry over her body. Zeref brought Mavis' body to the guild hall and after giving her body to Precht, he departed to his kingdom while tearfully stating he should have never fallen in love.
I have found that Ebay is one of the biggest places to find fake Hydro Flasks. The majority of Hydro Flasks listed on Ebay are fake, so you need to be really careful buying for Ebay. It's best to look at the used Hydro Flask listings for authentic cheap Hydro Flasks if you're going to buy from Ebay.