Arthur will be a) a giant mess and b) somewhat obsessed with commemorating the dead over in the AU - funky woad tattoos for the fallen, that is. These are totes visible (one's on the face, after all) and up for any notches-for-the-dead or whatever... stuff. (I mention this mostly because I'm a dork)

Otherwise, he's still trying-to-be-in-charge guy and will probably volunteer for just about anything of a patrolly or violent nature.

ETA: And just for full 'whee background disclosure' reasons, he and bigdamndestiny got their shit together (as in together together) fairly early into this particular nightmare, so that would probably be common knowledge to those who know 'em.