Rex

EDIT // I decided to change his appearance ! Also updated his info a bit.

This little cutie was adopted from Cioccolato-mousse 

Rex
Age: ??
Gender: male
Personality: He is really playful and likes to play. His way of playing is quite different (it often contains biting and/or eating the playmate). Usually very happy but when someone rebukes him or yells at him he gets melancholic, kinda angry and often confused since he doesn't understand what he did wrong. He doesn't understand the value of life so he doesn't understand why killing is wrong. He is often amazed by different colors and simple things for example colorful flowers or leaves falling from a tree.
Other: Pretty often there is some sort of toxic liquid or blood dripping from his mouth (toxic liquid can be any color). The liquid is not necessarily poisonous; it can actually even have healing effect. Whether or not the liquid is poisonous depends on his mood. His pupils can change shape the same way cats' pupils change shape. His height is about 25 cm.
Story: Rex has lived most of his life indoors. First in some sort of laboratory and then later in a huge abandoned building. Both of those places were dark and colorless so that's why Rex loves colors. His life indoors also explains why he is so amazed by simple things. 
Rex needs someone who takes care of him and travels with him. That someone probably helped him out of that building he lived in.