His Zodiac sign is Capricorn (B-day Jan.9) Do you see how this effects his character?

If he's anything like my son who shares the same birthday, then he would have been a very sweet loving boy with lots of empathy. And very very smart with a wicked sense of humor

Yes. Capricorns are resourcful, determined, stubborn, and very strict disciplinarians.
They also tend to have mood swings. They are quiet and subtle individuals who tend to have a sarcasttic sense of humor.
This is our lovely potions professor.

Astrology is an imperfect science, so to speak, and it is impossible to get a truly accurate picture of a person from just their Sun Sign. There is also their Moon Sign and their Ascendant (Rising Sign) that must be taken into account, as well as where the planets are set in their House Chart. Unfortuantely, to create an accurate Natal Chart & House Chart, the individual's exact time of birth and location must be known. Spinner's End is said to be located in Manchester, so we have the location, but we do not, unfortunately, have his time of birth.

Astrology is an almost life-long passion of mine and I've done a lot of charting. It's astounding how accurate a description it can give of a person when all the necessary information is provided. I would love to do his.