how to get each character of a textblock of different color in wpf?
Use many different runs:
<TextBlock FontSize="22">
<Run Foreground="Gold">H</Run>
<Run Foreground="Maroon">e</Run>
<Run Foreground="Blue">l</Run>
<Run Foreground="Orange">l</Run>
<Run Foreground="Brown">o</Run>
</TextBlock>
This produce the result: