i dont think eren become evil.
wat i read so far this come really close to guilty crown the person who earn the power is mabey in begin weak but start beging a ''Bad villain at some point'' as the viewer keep reader but at the last moment you see the Whole point as act of being the ''villain''
Earen though The titan where the Evil one but learned with time and some hint from other The Humantly where the one who Stared all this, Just like the greantperants or father said The World is the one who destroy everything or better say humantiy.
the place wat he just attack Where the one who Make everything worse in the world they Where the one who stared the war far from the beginning only for there ''fear as terror'' Ymir also said something about humanty als the world where the one who should be punshied not the titans. In my view as opstion and i think mabey other do they that why too.o.
idk why BUT i feel like Eren is going to turn into an evil character at the end