Grimlock is the leader of a group of Autobots known as Dinobots.
There's a popular misconception that Grimlock is a dumb evolutionary throwback. Maybe it's his taciturn, almost ponderous nature, or his clipped, stunted speech patterns. Or maybe that's just what Grimlock wants you to think!
In fact, Grimlock is a shrewd and frighteningly effective warrior and commander, with little time for mercy and compassion.
Legends of the Multi-Universe (Menslady's story)
However, when it comes to being around the Children of the Autobots, Grimlock is willing to put everything he can into acting as gentle and loving as possible toward his kids.