This is Margaret with a fourth (two boys, two girls - an even playing field), but... probably not a final.
You're looking at John (CALLED JACK) Clarke. He is the final dorm mate of the Marauders'~ That means he is a sixth year Gryffindor with a loyal streak who is just coming out of his youthful, arrogant days. His mother died this past summer so you can expect that he is a little more mellow than he would have been last year, but he is still a very lively young chap. You can expect he'll need friends and enemies (he's a Half-blood).