Unfortunately we do not offer a RichText to help you in this case.
I can only suggest things that you have probably though of already:
- Bind to several TextBlocks instead of one, this is not very maintainable though.
- Bind the Content property of a ContentPresenter and use a Converter for the binding (IValueConverter) that will take the required property and generate a TextBlock with the required colored runs.
the Telerik team