Full name: Matilda Frigga
Hair colour: Brown
Eye colour: Blue
Personality (when older): Matilda grows to be a very mature young woman with a short temper. She's sweet but can be harsh.
Weapon (when older): Is given a Hammer much like Thor's to control lightening
Other information: Being born first and four years before her younger brother Matilda was always the centre of attention up on Asgard. However when George was born Matilda happily gave away the attention for her brothers happiness.

Full name: George Loki
Hair colour: Brown
Eye colour: Brown
Personality (when older): George is like his Father when he gets older. He enjoys showing off and is a hit with the ladies.
Weapon (when older): Is trained in all weaponry, Asgardian and Midgardian.
Other information: When Jason was born George didn't like his younger brother by a year. But over time he and Jason became the best of friends.

Full name: Jason Odin
Hair colour: Blonde
Eye colour: Brown
Personality (when older): Jason grows up to be very talkative, about anything. He makes good arguments and can talk about what he knows for days.
Weapon (when older): Prefers to stay in the lab like his mother but can shoot a gun.
Other information: Jason was the last born to Thor and Jane and his older siblings were always around. Jason would rather just sit with his siblings rather than playing with other children.

(I'm not sure how to do last names of Gods so I've just done first and middle names for the children.)