Rhys Williams, a 22-year-old defender, saved the center backs from a doomed situation in the 2020-21 season with Nathaniel Phillips.
He has been on loan briefly to Swansea and Blackpool after failing to get a chance to start since the regular center backs returned to the squad.
However, he has been unable to get a regular role in the new clubs, and his loan move to Blackpool last season was cancelled earlier than planned and he returned to Liverpool, where he has been playing in Premier League 2 ever since.
His first-team opportunities will be limited next season, and there have been rumors of a loan or a complete transfer, but the young center back has decided to join Aberdeen.
The term is for the whole of next season and he will spend the 2023-24 season in Scotland.
He will once again be a colleague of Leighton Clarkson, who joined Aberdeen on a permanent transfer this summer and has vowed to make a big step forward in the Scottish Premiership.