Given 2 files and a build target, how to identify which is a dependency of which in Bazel?

I have a "file.py" and "other_file.py" that are both somehow a part of bazel run my:target. Is there a way to tell in the dependency tree would target of "file.py" depend on target of "other_file.py", or vise-versa, or would they both have a common ancestor.

You can use bazel query for this: https://bazel.build/query/guide

E.g. for:

py_binary(
  name = "main",
  srcs = ["main.py"],
  deps = ["file", "other_file"],
)

py_library(
  name = "file",
  srcs = ["file.py"],
  deps = [":other_file"],
)

py_library(
  name = "other_file",
  srcs = ["other_file.py"],
)

bazel query --notool_deps --noimplicit_deps "deps(main)" --output graph | dot -Tpng > /tmp/graph.png

produces

To do the reverse:

bazel query --notool_deps --noimplicit_deps "rdeps(//..., other_file.py)" --output graph | dot -Tpng > /tmp/rdeps_graph.png