Germaine Greer has a really interesting article in the Grauniad about the Newbattle portrait of John Donne, and I like her theory that Donne's ,elancholy is more the result of grief and doubt than a pose calculated to get a girl into bed.
http://www.guardian.co.uk/arts/features/story/0,11710,1696541,00.htmlThe picture is interesting in itself, though; it strikes me as bearing a certain resemblance of how a lot of fangirls see Snape.
On the other hand, it would make an awfully good Sirius, epsecially if you adopt the Greer reading (we have an overbearing mother, a dead brother who was the 'good son' and the subject himself increasingly alienated from his childhood beliefs). Or alternatively, you could make it Regulus, brooding over what to do about his suddenly unwanted tattoo...