The character has to be: positive, friendly, inviting, calm, inteligent, simple, smart and a bit fun.
My first idea was inspired from a character of American TV series Shameless – aunt Ginger. She is very polite and good with anyone and sometimes knows more things than the others, although she is mentally ill.
However I couldn’t find any good 3D or concept art picture references or something that can help me draw a similar character so I started experimenting, redrawing some other popular 3d characters and slightly changing them.
My final choice was a simple boy/man with exaggerated head size which symbolise the size of his intelligence and a smaller body about the size of his head. His arms and legs are even smaller, almost like a sticky man.