The offer

Harry stared after the Elf as he popped away. Kreacher had after long protest accepted a closet as his room, in which Harry had put the painting of Sirius’ mother. Kreacher had had no problems removing it from the entrance wall, and now the evil woman’s painting hung there, with only Kreacher for company. Somehow it made the both of them happy, and Harry had a neutral entrance back. Instead of Walburga Black, there was now a painting of Sirius, Remus and Nymphadora Lupin, and Fred Weasley, sadly a non-magical one but still a nice way to honor the fallen heroes.
Harry walked past the painting up the stairs to his room… and froze in place. On his bed were Hermione, Luna, and Ginny, all lying down wearing only bras and knickers, all facing the door.

“Hi Harry,” the trio said in unison, grinning. Luna took Ginny into a deep kiss, and their hands rubbed each other up and down. Hermione rolled on her back, looking at Harry upside-down. Her prominent breasts were clearly on display in this position, and she had one leg slightly raised, the other flat, giving her a bit of cameltoe.
“What… what are you three doing?” Harry gulped. “Not that I mind you being here, you’re always welcome…”
“Well, I had something in mind,” Hermione cooed. “And I think you’ll like it, Harry. Now I know you’ve been dating all three of us off and on, but have not decided on who you want to be with.”
“And yes Harry, we know about each other, and we know you’re not cheating as you always waited until we broke up before you dated the next one,” Ginny added, then gave Hermione a full kiss on her upper neck.