Fremantle finally have Cam McCarthy, securing him from the Giants in an AFL trade a year after their first attempt.
This year's first AFL trade involves the Dockers giving up pick No.3 in the national draft.
In return they receive McCarthy plus picks seven, 34 and 72.
The Giants knocked back Fremantle's efforts to recruit McCarthy, a WA native, a year ago.
The 21-year-old then sat out this season because of mental health issues.
Fremantle have been linked to WA-born forwards Cale Hooker (Essendon), Jesse Hogan (Melbourne) and Rory Lobb (Giants) - but all have re-signed with their clubs.
The Dockers need to boost their forward stocks following the retirement of captain Matthew Pavlich.
McCarthy has played 21 senior games since his 2014 debut.
Last season he showcased his potential with 35 goals from 20 games.
"We're really excited about getting Cam to Fremantle," said Dockers list manager Brad Lloyd.
"He's a talented young player who is a proven performer at AFL level."
The Giants released McCarthy from the last year of his contract and their football manager Wayne Campbell said that was in everyone's best interests.
"With Cameron's strong desire to return to WA, we worked closely with his management team to facilitate a deal that we feel benefits everyone involved," Campbell said in a club statement
"Cam's welfare was always the priority for everyone at the Giants and the club wishes him the very best.
"Securing the third pick in the draft is significant as it puts us in a strong position to further enhance our playing list."
