The 20-year-old joined Leeds on loan from Swansea this week.
The 20-year-old joined Leeds on a season-long loan from Swansea City this week, becoming the club's fifth signing of the summer, with striker Kemar Roofe making it six by joining United later on in the day.
The former Exeter man, who played under manager Garry Monk at Swansea, came in shortly before Lewis Cook joined Bournemouth in a potential £10 million switch.
Grimes also had a stint with Blackburn Rovers last term, but many Leeds fans will not know a great deal about the man himself or what he can bring to the side.
He told LUTV when asked what Leeds fans can expect from him: "I like to play as a number eight, so I like to drop deep, get the ball and start the moves. I like to get forward and nick a few goals as well if I can.
"I just like to contribute to the team. I always wanted to play it [the ball] forward and not playing safe and boring football, which is one of my pet hates really."
With the exception of Roofe and Grimes, Leeds have also brought Marcus Antonsson and goalkeeper Robert Green on permanent deals, while Kyle Bartley and Hadi Sacko have joined on loan.
It has certainly been a busy summer for Leeds in the past couple of weeks, and Monk will hope his new boys hit the ground running - they have to.
The reality at Leeds is that the former Swans boss will not be given a great deal of time. If his history wielding the axe on managers is anything to go by then owner Massimo Cellino will want to see instant results.