Eren Jaeger is your starting character and also the star of the Attack on Titan anime and manga, so of course he’s going to be a bit special. When you first obtain Eren, his starting skill, Reckless, actually decreases your Leadership stat even more. However, that skill is swapped to Transformation after you beat the main story, giving you the ability to become his Titan Form instead of using a Decisive Battle Signal.
His concentration makes his Focus and gas usage much better than most, so he has that going for him. Also, he can move normally even when critically injured, which will help you in tougher fights down the line.