Megan Fox is one hot — and capable! — stepmom.

Fox's husband Brian Austin Green has high praise indeed for her devotion to Kassius, his 8-year-old son with ex Vanessa Marcil.

"[Megan] is absolutely my better half in parenting," Green, 37, says of Fox, 24, in the October issue of Details. "She just gets it. It's instinctual for her."