Jasper

Jasper is the relationship between Piper mcLean and Jason Grace in the Heroes Of Olympus fandom.

Canon
In The Lost Hero, when Jason first meets Piper on the Wilderness School bus, and once he was resting on Piper he calls here "pretty", but he does not recognise her since they had never actually met at that time. Jason and Piper hold each other face-to-face when Jason saves Piper from falling down the Grand Canyon. He mentions that he could not pretend that he was not a little tempted to kiss her when they held each other like that. Jason mentions that he did not leave her when she was knocked out.

Piper developed feelings for Jason during the school year, but he was not actually and it was all a trick of the Mist. When Aphrodite claims Piper at camp, Jason calls her a "knockout" because she's so beautiful in his opinion. It is also revealed that Jason was very protective of her when she was knocked out due to the vision from Hera/Juno.

They bond during the quest, wrapping arms around each for different reasons, and at the end of the book they meet at the basketball court. Over there, they don't kiss, much to the dismay of the Aphrodite campers who had been betting on that. Piper also tells Drew Tanaka to back off from him because earlier in the book Drew had been flirting with him.

In Leo Valdez And The Quest For Buford, Leo states that the two are now an official couple, and that Piper looks a lot happier. She also gives Jason a goodbye kiss in case she never sees him again.

In The Mark Of Athena, Annabeth addresses Jason as Piper's boyfriend, which shows that the two have officially started a romantic relationship. Jason reveals to Piper that he prefers her over Reyna on the Argo II. Piper tells him that she loves him while they are drowning, even though they both survive.