Sometimes, people tend to forget that Humanity's Strongest is still just a normal person who is just trying his hardest to live in this cruel world that he have been thrown into and that Humanity's Hope is just a 15 year old boy who have seen too much yet too little.
Other times, they just try to ignore the fact that they're relying on humans much like themselves. Just so that they have someone to blame every single time something goes wrong. The only ones who understand their cruelty, are the ones who are being blamed. Namely Humanity's Strongest, Coporal Levi, and Humanity's Hope, Eren Jaeger.
Both forced to take on a title neither wants. Sure, both wishes to kill titans for what they both lost but that doesn't mean that they can hold the resposibilty. Levi may be an adult but then again when was he not. And Eren, he's just a 15 year old boy who just realised he can change into a monster. The same thing that killed his mother and many others.
But what can they do about it? The answer, nothing. They just can't do anything about it, other then feel sorry for themselves.