Not much is known about the history of this incarnation of Jack Power/Mass Master prior to his first appearance.

He is the second son and third child of James Power and Margaret Craig. He is 10 years old[2], which means he was 9 years old when he received his powers from Aelfyre Whitemane [3]. This makes Jack at the moment 2 years older than his Earth-616 counterpart was upon receiving his powers.

Brash and ornery, Jack Power is the "wild child" of the Power siblings; probably even more so in this reality than in Earth-616. He frequently insulted and argued with both his teammates and his adversaries and can be very stubborn. He is however good friends with Franklin Richards, with whom he shares a taste for causing mischief and having adventures. Jack is a great fan of the Japanese Game Show "Ninja Master", and once signed up his brother Alex for this show. He also likes to make videos about the teams' training sessions.[4]


Primarily, Jack has the ability to control the density of the molecules of his body. He can disperse his molecules into a dense, cloud-like form, or reduce the space between them until he is a small, highly resistant 8" size. He has also shown the ability to materialize only a portion, or just a part of his body, like making his upper body solid while his lower half stays in cloud form.

In Earth-616, when his sister Julie had the powers as Molecula, she discovered that she could also assume an 8' form that was nearly intangible. It is unknown if Jack of Earth-5631 ever had this degree of control, or if he ever switched powers with his siblings like his Earth-616 counterpart did.

Strength level

Normal human child with regular exercise.


Power Pack Uniforms

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