Proteus, like the other inner moons of Neptune, is unlikely to be an original body that formed with it, and is more likely to have accreted from the rubble that was produced after Triton's capture. Triton's orbit upon capture would have been highly eccentric, and would have caused chaotic perturbations in the orbits of the original inner Neptunian moons, causing them to collide and reduce to a disc of rubble. Only after Triton's orbit became circularised did some of the rubble disc re-accrete into the present-day moons of Neptune.
Proteus, like the other inner moons of Neptune is unlikely to be an original body. that formed with it, and is more likely to have accreted from the rubble that was produced after Triton's capture. Triton's orbit upon capture would have been highly ec,centric, and would have caused chaotic perturbations in the orbits of the original inner Neptunian moons, causing them to collide and reduce to a disc of rubble Only after Triton's orbit became circularised did some of the rubble disc re-accrete into the present-day moons of Neptune.