Found sweet gray cat (Edgewater/Lakeview (63rd & Portland NW))

A sweet little gray cat that is clearly someone's pet has been hanging around for food.
We cannot keep it, so I'm hoping its owner is simply missing it, and didn't dump it.
Don't know yet whether male or female.
All gray with small white patch on its chest and slightly darker gray stripes on its tail.
Looks like it's (part) Russian Blue.
He desperately wants in, but our cats want to kill him and we have a cat with FIV, so it's a no go.