How to set this up?

I wonder what could be the best way to approach this:
I like to have a long text appearing character-by-character. And some logic to trigger the character appearance. Letters do not have to appear from start to end, but in random mode. Somehting like this:

Any idea how to do that?

try this, it splits the characters and uses woeis BuildSpread to set the aplha values. (7.1 kB)

Or something Like this

TextCharacters-2.v4p (37.5 kB)

You guys rock.
Thanks so much.