The Additional Houseguest
A former California friend annually attended the famous Cannes Film Festival in France for a few years.
Along with some festival-attending friends she'd made in previous years, for the 2008 festival a small villa was rented.
To spread out the rental costs as efficiently as possible, they pretty much had it filled up.
But one guest never paid... but then... this houseguest clearly already dwelt there.
Some of the guests began to feel a presence there during their stay.
Once while my former friend was chatting with two of her friends, small objects on the table began visibly being moved about.
My friend's friends were a bit taken aback, but my friend told the entity to cease, and the activity stopped.
This almost concerned her two friends more than the activity.
(On her return, I admonished my friend for halting the obvious high-level of paranormal activity without first getting video footage of it taking place.)
In France, my friend suspected it might be
her own house ghost,
having come along with her, even though back at her place
(where I was house and dog-sitting),
her dogs occasionally during my stay were still reacting to that ghost's presence there;
personally I am pretty sure whatever my friend experienced in France was that of a totally different entity.
Unrelatedly, my friend slowly began to spiral into mental illness, OCD taking over almost her every waking moment.
The time came that we had to part ways, her mental illness grown to such an extent she severed relations with me.