Penrith expect Ivan Cleary to step down as head coach after the 2027 season; Liam Martin may also leave.
Jett Cleary will return to the club on a two-year contract beginning in 2027.
Nathan's younger brother debuted in the NRL for the Warriors late in 2026 and impressed in NSW Cup.
He is expected to push for a first-grade partnership with Nathan.
Nathan is reportedly in the final stages of negotiations to remain at Penrith, having turned down the PNG Chiefs and other rivals.
His contract could be worth up to $1.7 million per season.
The brothers want to play together, and Nathan previously said he would not join the Warriors while Jett was there, to avoid standing in his way.
Blaize Talagi could leave if he finds another deal, while Jack Cogger is the other halfback option.
Jack Cole is departing for the Perth Bears' inaugural season, and Penrith are expected to confirm Isaah Yeo's extension soon.