Humanity's Strongest Soldier- [Ereri/Riren]

In which the question that's asked and answered is, what if Levi and Eren switched places (roles, ranks, ages, etc.)?

Could we have a better outcome?

The War against the titans is fierce, but this time around the insignia of freedom has not been completed.
Lance Corporal Eren Yeager is well known as Humanity's Last Hope, due to the fact that he posseses no titan [shifting] powers but in a rage can cause them to cluster attack on a single one, a power granted to him by his father through an injection when he was at a young age. The Survey Corps regiment is still set on finding the basement.
But everyone knows- Eren especially- that Hope is nothing without strength, reason being Humanity's Strongest Soldier has still not been found [Why it's not Mikasa will be explained].
Then, the Survey Corps are notified of a cadet who has the miraculous ability to shift himself into a titan; little do they know, this cadet is a rebellious brat who crosses way too many borders, ones that lead straight into Humanity's Last Hope's Heart.