The epilogue of the Book of Atrus contains [spoilers]
his monologue at the beginning of Myst that ties events to Riven.
It also describes a scene where...
Atrus and Catherine (Katran) are looking out over Myst Island admiring their two young sons who are playing with Anna.
Other than that, there is little to no mention of the details of life for Atrus and his family prior to his sons betrayal except for what is told in his journals nor is there much that is ever said in much coherent detail about events that took place while the brothers were on their spree.
Details in Myst are vague as to events that took place during the brother's rampage but some things are elaborated upon in Myst IV. It sure would be interesting to have a more thorough account of Atrus' adventures with his sons on Myst Island as well as more of what the brother's were up to during their spree.
there is also a comic book by Hyperion iirc called the Book of Black Ships that told of Sirrus and Achenar's tenure with the black ship pirates mentioned in Myst. However, though I've never read it (nor do i have any idea where it could be found) I hear it's less than good and it's also not considered Myst cannon.