The old cliche of big empty mansion with two horny men investigating the house; maybe the house is near one of their relatives.
If you want to do AU, Ben is the academic who scoffs at the idea of REAL paranormal activity who's dragged into the investigation because he's preparing a dissertation on the views of modern humans on the paranormal while Simon is a paranormal investigator with his own burgeoning cable show who needs Ben's support to launch his career in more respectable circles. Cue weeks spent in a dilapidated house with rising UST and creepiness while they argue and bicker.
[RPF] Ben/Simon Haunted House (optional AU)
If you want to do AU, Ben is the academic who scoffs at the idea of REAL paranormal activity who's dragged into the investigation because he's preparing a dissertation on the views of modern humans on the paranormal while Simon is a paranormal investigator with his own burgeoning cable show who needs Ben's support to launch his career in more respectable circles. Cue weeks spent in a dilapidated house with rising UST and creepiness while they argue and bicker.