Is it possible to have a mod to give portraits to characters who don't have one?

[house2fly]

There's all these portrait packs floating around, and there's all these characters like the Duc and Adaryc who really should have portraits but don't... is it at all possible to make it so that their conversations are capable of showing a portrait when they speak? Then the user could choose a picture to make their portrait and boom. Probably not but figured it can't hurt to ask.