I just found this and while I can honestly say I have not read any lovecraftian novels, I have played call of cuthulu tabletop for a year now and love it. My DM specifically asked us to not read any of the lovecraft novels to prevent metagaming.

The character I play there (and thus would play here) is originally a cat-burglar who discovered he could use arson to cover up his robberies. He always made sure to never kill anyone and only target the rich usually when away from their second homes for the season. He eventually got caught and claimed pyromania/pyrophylia ("the fire is my mistress and I am her lover") and got locked up in the assylumn instead of jail. It was there that he saw something wholly impossible and it shook his sanity for a long while as one of the inmates escaped through unnatural means (gradient level between using telekinesis to open his door from the inside to summoning something to help him break out.) My guy used the ensuing chaos to break free as well and escape with the others.

Sine he is truly a criminal and not a lunatic, it was easy enough for him to back to his old ways, but that taint of what he saw lit a beacon for the weird of the world to follow him and he doesn't know why.