Why does Miquella have a malicious intent?

I just finished SOTE and it was absolutely amazing. It truly astonishes me how Elden Ring can be that perfect in that way in my opinion.

After killing Consort Radahn after around 500 tries, something confused me.

Why does Miquella seemed evil in a way? He charmed his own brother, only too use him as some kind of bodyguard or too ascend to godhood. And he used his other half-brother Mohg, charming him and manipulating him.

Honestly, I expected Miquella to more good than evil, but he isn't.

Anyone got any thoughts on this? I really want to know why this dude basically wanted too spread the word with his "compassion" or whatever the means.