Pebble

Ares and Pebble come from a postapocalyptic universe, where a natural  disaster happened that destroyed most of humanity and robots took over  the planet. Humans who survived tried to fight back against the robots  and get back in control, but to no avail. Most of them were captured and  enslaved by the robots. The sisters witnessed their parents deaths when  they were trying to protect them from the robots and right as the  robots were about to get them a portal appeared, They didn't think and  jumped through ending up in CBU's sea.
Pebble can't swim, so Ares had to carry her all the way to land.
When  they got on land there were monsters attacking them.. Ares was  exhausted and fainted so Pebble attempted to throw pebbles and rocks to  defend themselves, screaming for help. Luckily the rangers came in time  to rescue them.