Mercury is a relatively shy planet and is easily intimidated. Due to him being the smallest planet in the Solar System, he often gets thoughts on what happened with Pluto (demotion from Planet group). Because of his small size, he is often the target of bullying by Venus, and occasionally, Earth. He is good-natured and careful with his words, (which is now debatable considering he called Earth’s attempt a “stunt”) and he tries to avoid hurting the feelings of the Sun when he asks if they are friends or not. Mercury is slowly becoming more tolerant and assertive, standing up to both Venus and the Sun.

Venus is a short-tempered rocky planet who gets aggressive when provoked too much. He hates the fact that he was named after the Roman goddess of love and beauty, which the other rocky planets would occasionally tease him for. He is usually seen being dominant towards Mercury which he would make the latter stay in his orbit, rarely allowing him to interact with the other planets sometimes, even bullying him verbally by calling him 'pipsqueak' because of his small size. Venus also nearly killed Mercury by throwing an asteroid at him in a fit of rage after the latter teased him for it. He also likes Theia, but Theia likes Proto Earth later on in the chat.

Theia was a kind and caring planet, she was worried about Earth and pleaded him to wake up. She was shown to be a polite planet. She took first impressions seriously and when interrupted by Proto-Earth she shows to hold a grudge against him and asking Proto-Earth to apologize to her after feeling ridiculed in front of everyone. Theia also can be skeptical at times, as she felt suspicious after the Sun said "I have big plans and they definitely involve you guys not dying.”

What can be gathered of his personality is that he was pretty cocky and arrogant, similar to the Earth pre-Moon Revolution. His main feature was that, unlike Theia and present-day Earth, he initially didn't believe he could support life.

Mars is generally outgoing and friendly and is shown to encourage and inform other celestial bodies.