If a positive charge (A) were to enter the electric field of negative charge (C), what would the forces look like?

A <-- C <-- A
B C <-- <-- A
C <-- C A -->
D C <-- A -->

The positive charge A would be attracted to the negative charge C, so it would experience an attractive force towards C. The negative charge C would also experience an attractive force towards the positive charge A. This would cause both charges to move towards each other along the electric field lines.