Jack Sheriden

Jack Sheriden was a young rookie cop in the Central City Police Department and the new partner of Joe West.

The Flash: Season 5
He was introduced to Joe West as his new partner at the Central City Police Department by Captain Singh who wanted Joe to take Jack along and teach him things. Getting used to each other, Joe wanted to go to his associates at STAR Labs when they get a new case of a series of mysterious murders and after investigating them, they realize all victims are Metahumans. Not feeling indifferent to anything, they work the scene until they are called in to take Gridlock into custody again which they did. Nor Jack or Joe was on the transport of Gridlock when it was attacked and Gridlock was murdered by a mysterious attacker.