I'm using a font with "calt" (contextual alternates) on LuaLaTeX - as a matter of fact, BemboBookMT. So, for example, Q has a "tail" when followed by a u:
When I use lettrine, I get a standard Q even if Q is followed by a u: possibly because LaTeX doesn't "see" the chain due to lettrine implementation.
A possibility I see is to manually select the alternative glyph; with
I obtain a long-tail Q even in Lettrine Though, this is a bit tricky, and I wonder if there's a better way to deal with the issue. For example adjusting the font features through Lua. Perhaps there's a way to code the chain substitution, provided that you know how lettrine exactly works...
I thought also of setting the long tail Q as default (with a type = "substitution" feature), and then set a "chainsubstitution" feature only for the cases where I want the standard tail. But I didn't manage to make it work.
EDIT: Here an example of how the desired output could work: