He wasn't all there before this started, and has only gotten worse.
Julian was a loner with mild sociopathic tendencies before the dead started rising, so it's easy to see how his mental condition hasn't improved much since. He loathes company unless he sees something of value in an individual or group, preferring to live, sleep and survive alone. He will often believe he is seeing things that aren't really there, hearing things when no noises are being made, and becomes paranoid of others very quickly and often for no reason at all. If spoken to he will say very little and in a halting and jittery tone, obviously uncomfortable, but it has been said he only ever looks at home and even (quite disturbingly) happy when killing one of the walking dead that roam the city streets outside. Julian makes others uncomfortable and people who come in contact with him invariably feel the need to stay at arms length from him, and not just because of the smell.
Snub nosed 9mm revolver, 4 rounds left
Small backpack with sleeping mat and food
Julian had a fairly regular life before the world went to hell working as a software analyst for a small accountancy firm in the city. He had few interests, fewer friends and spent his time when not working either reading, watching television or walking the nearby parks with no particular aim. He regualrly visited his psychologist and took his pills, allowing him to live a bland but peaceful life. He was never content however, only partly fighting some of the more worrying 'urges' that crept from his mind in the small hours and letting his medication fight the rest. His shrink was only just getting to understand these impulses he had before he found her lying in her office minus her face in the first day of the undead takeover, and so she never truly understood what the quiet, retiring man could be capable of.
In the first few weeks Julian kept to his apartment building, but soon his food, water and medication were all running out and he was finding it increasingly difficult to keep the undead residents of the building from getting onto his barricaded floor. Since then he has moved from place to place, learned from scratch how to stay alive, and searched out of habit more than anything else for the medication he had taken since he was a child. It was a long time ago he had taken any pills, however...