I like Severus’ calm, trusting look and Harry’s deep concentration on what he’s doing. And all the touching! Especially Severus’ fingers on Harry’s chest because it’s so casual, like they can be that intimate without actually being intimate. I don’t know how else to say it, except that it’s obvious they love each other. In the same way, the unhesitatingly displayed Dark Mark reveals how close they have become and how strong their relationship is.