That's a different story haha (≧▽≦) while reading this comment I feel like I'm reading a fanfic. Eins wanted to be king at first because he's being pressured (inclusion of vol.16) but after meeting Heine he change his mind and he wanted to become king because he wanted to. Ernst on the other half already became his ideal self with the help of Eins so he wanted to help him to be king whatever it takes.
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Their kind of love is either the love of lovers or love of friends, or even family, but their type of love is something that's to precious to break that's why it's sometime mistaken as you guys know— the author confirmed that haha—
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And yes, Eins is in loved with someone else already.
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Wait for the update for you guys to know hehe—
What if eins and ernest are lovers? Im not turning this into yaoi but being in a same relationship can caused a huge issue in palace. So ernest ofc wants eins to be the king. But eins knew he cant but will do everything for ernest. Its like i will expose our relationship if you’ll fail to be a king. Something like that.
Or maybe when eins was young, the wet nurse change the baby upon delivery? Because the real eins died? So the queen is the only one who knew everything. And ofc ernest found it out and use it against eins. So eins will do what it takes to hide that past.