User blog comment:Mathias Custos/Could there be a fourth?/@comment-3146930-20131221140004/@comment-3257939-20131223041806

Penny's robotic attitude could be due to being isolated from the world. When she met Team RWBY and when she appeared in the final episode, her driver said that she shouldn't be running off, implying that she had to escape from her home to have some freedom. And her driver refers to her as Penny and not Miss or My boss' daughter. If Penny has to spend most of her time in her home, it's normal that she became good friends with the butler or the driver.

Sun is still unknown affiliation, he was at the ship but maybe just to steal some bananas. He is stronger that Blake since he was able to fight Roman without getting hit while Blake was knocked out, that proves that he is well trained. He could even be a second year or a senior at the school he belongs to.

Velvet has a team and she has a lot of experience in teamwork, as stated by Monty himself.