How Love Goes
It had happened in the library at one of the sets of couches along the back wall. He’d been struggling with an essay for Arithmancy while Theo sat beside him on the couch, relaxed back against the armrest, and reading a book for Muggle Studies. In a moment of frustration, Harry leaned back and ended up somehow resting on Theo’s chest rather than the back of the couch.
Or: The time in Eighth Year when Harry realizes he might have feelings for Theo.