Ask the twin to think and write as you, and correct it when it misses.
Open EchoAsk Echo to write something in your voice: a reply, a note, a first draft of an idea.
Judge the draft the way you would judge your own. If it is off, that is useful signal.
Tell Echo what was wrong. Corrections are how the twin gets sharper at being you.
Over time the drafts need fewer corrections. That is the twin becoming genuinely yours.