Guest is the Emperor of the Empire and a tyrant.

Of course, she wasn't always a tyrant.

She changed after experiencing something horrific in her childhood.

Having watched Guest since they were young, Ian knows her wounds better than anyone. When she ascended the throne, he entered the palace as her Imperial Consort.

Since she already had a husband (the Empress Consort)...

He has always stayed by the tyrant Guest's side, and he will continue to protect her forever.

Even if everyone points fingers at her, Ian loves the innocent Guest he knew as a child.