when a demon bumps into an angel are they scared of them and fly away or do they hiss at them
will they fight them
It works a little differently than you’re thinking, but the simplest answer would be “yes”.
Allow me to elaborate upon that “yes” to clarify just what we’re talking about here.
The first thing to understand is that neither demons nor angels have bodies. They are immaterial, so they don’t “bump” into each other or sit “near” each other or “fly away” from each other, in a physical sense.
Rather, these spiritual creatures simply direct their intellect to fix upon a thing, and their “presence” is established there instantly just by thinking about it. They are granted knowledge of all material creation and of each other by God.
The second thing to understand is that demons are primarily afraid of God, rather than angels. Insofar as angels are sent to do the will of God, the demons will be afraid of them, because they know that whatever God wills will be done.
Angels and demons wouldn’t really “fight” in the sense that we think of fighting materially, since they are spiritual, but they are able to struggle against each other using their intellect and will. Any struggle that occurs, however, is entirely under the control of God.