Across the alley is a reference to cutting yourself self-harm is defined as the intentional, direct injuring of body tissue, done without suicidal intentions. this one refers to the most common form of self-harm is using a sharp object to cut one's skin going across the arm and now down the arm
A way of conveying a location (e.g. a building) that is across a roadway from another location. It doesn’t necessarily mean directly across but can also refer to a location that is at least a block down the road and across.