Harry should think of Voldemort. They all tell him that on a daily basis. Hermione insists that he study extra. No, nothing for the NEWTs, even she has reassessed her priorities. Staying alive seems to rank above school performance now. Ron talks to him about strategy and positioning. Dumbledore...Harry isn't sure that he understands what Dumbledore tells him, but then he stopped trusting the headmaster when Sirius died. Snape has been coherent through the years, telling him that his idiocy will kill him right before invading his mind under the pretence of teaching him.
Harry knows he should be listening to them. His life is more important than anything else. Or is it?
Christmas hols, and everyone is at Grimmauld Place, but it's easy to think of something else, to cast a silencing charm, and wait for Bill to slip into his room, wait for his lover to drive him mad with need, before screwing him through the mattress until his arse is sore and his voice is hoarse, and to wait until he can fall asleep in his lover's arms.
In the mornings, when he opens his eyes and watches Bill, Harry knows that there is something more important than anything else: Bill.